3,462 results on '"Symporter"'
Search Results
2. Sodium iodide symporter immunolabelling as a predictor of clinical iodide uptake in canine thyroid carcinoma: A preliminary study.
- Author
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Dark, Katelin V., Skinner, Owen T., Kim, Dae Young, Karnia, James J., Mickelson, Megan A., and Maitz, Charles A.
- Subjects
- *
SODIUM iodide , *THYROID cancer , *THYROID gland , *ION traps , *IODIDES , *POSITRON emission tomography computed tomography - Abstract
Thyroid follicular tumours may take up iodide via the sodium‐iodide symporter. Knowledge of iodide uptake could then allow treatment with I‐131 in dogs with high‐risk tumours. The objective of this study was to determine the relationship between clinically detectable iodide uptake (as determined by scintigraphy and/or thyroxine concentrations) and sodium iodide symporter immunohistochemical labelling on histologically fixed thyroid tumours. Nineteen dogs were identified who were diagnosed with thyroid carcinoma and underwent surgery from November 2017 to July 2021. All had recorded thyroid hormone concentrations and were hyperthyroid and/or underwent preoperative nuclear imaging using planar scintigraphy (technetium‐99m or I‐123), or I‐124 PET‐CT. All dogs subsequently underwent surgery to remove the thyroid mass. Twenty‐two tumours were submitted for histopathologic analysis immediately following surgery, which confirmed a diagnosis of thyroid carcinoma for each tumour. Images and/or thyroid hormone concentrations were reviewed for the included cases, and tumours were sorted into an avid/functional group (group 1) and a non‐avid/functional group (group 2). The tumour tissues were re‐examined histologically using sodium iodide symporter (NIS) immunohistochemistry (IHC). Group 1 contained 15 avid/functional tumours. Twelve of these tumours had membranous NIS IHC labelling. Group 2 contained 7 non‐avid tumours. One of these tumours had membranous NIS IHC labelling. This resulted in an overall sensitivity and specificity for identification of avid/functional tumours with membranous NIS of 80.0% and 85.7%, respectively. NIS IHC may predict ion trapping in canine follicular thyroid tumours. Further studies using iodide‐based imaging are warranted to better determine the clinical utility of this diagnostic modality. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Lactose Permease Scrambles Phospholipids.
- Author
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Wang, Lei and Bütikofer, Peter
- Subjects
- *
PHOSPHOLIPIDS , *LACTOSE , *AMINO acid residues , *MUTANT proteins , *GALACTOSIDASES , *CARRIER proteins - Abstract
Simple Summary: Scramblases are proteins that translocate phospholipids from one leaflet of a membrane bilayer to the other. Our work identifies that a well-characterized protein from Escherichia coli, lactose permease, also displays lipid scrambling activity. The scrambling function is independent of LacY's proton-coupled lactose transport activity and involves two amino acid residues located near the membrane surface. Lactose permease (LacY) from Escherichia coli belongs to the major facilitator superfamily. It facilitates the co-transport of β-galactosides, including lactose, into cells by using a proton gradient towards the cell. We now show that LacY is capable of scrambling glycerophospholipids across a membrane. We found that purified LacY reconstituted into liposomes at various protein to lipid ratios catalyzed the rapid translocation of fluorescently labeled and radiolabeled glycerophospholipids across the proteoliposome membrane bilayer. The use of LacY mutant proteins unable to transport lactose revealed that glycerophospholipid scrambling was independent of H+/lactose transport activity. Unexpectedly, in a LacY double mutant locked into an occluded conformation glycerophospholipid, scrambling activity was largely inhibited. The corresponding single mutants revealed the importance of amino acids G46 and G262 for glycerophospholipid scrambling of LacY. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
4. Mobile barrier mechanisms for Na+-coupled symport in an MFS sugar transporter
- Author
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Parameswaran Hariharan, Yuqi Shi, Satoshi Katsube, Katleen Willibal, Nathan D Burrows, Patrick Mitchell, Amirhossein Bakhtiiari, Samantha Stanfield, Els Pardon, H Ronald Kaback, Ruibin Liang, Jan Steyaert, Rosa Viner, and Lan Guan
- Subjects
membrane protein structure ,cryoEM ,nanobody ,H/D exchange-ms ,symporter ,ITC binding ,Medicine ,Science ,Biology (General) ,QH301-705.5 - Abstract
While many 3D structures of cation-coupled transporters have been determined, the mechanistic details governing the obligatory coupling and functional regulations still remain elusive. The bacterial melibiose transporter (MelB) is a prototype of major facilitator superfamily transporters. With a conformation-selective nanobody, we determined a low-sugar affinity inward-facing Na+-bound cryoEM structure. The available outward-facing sugar-bound structures showed that the N- and C-terminal residues of the inner barrier contribute to the sugar selectivity. The inward-open conformation shows that the sugar selectivity pocket is also broken when the inner barrier is broken. Isothermal titration calorimetry measurements revealed that this inward-facing conformation trapped by this nanobody exhibited a greatly decreased sugar-binding affinity, suggesting the mechanisms for substrate intracellular release and accumulation. While the inner/outer barrier shift directly regulates the sugar-binding affinity, it has little or no effect on the cation binding, which is supported by molecular dynamics simulations. Furthermore, the hydron/deuterium exchange mass spectrometry analyses allowed us to identify dynamic regions; some regions are involved in the functionally important inner barrier-specific salt-bridge network, which indicates their critical roles in the barrier switching mechanisms for transport. These complementary results provided structural and dynamic insights into the mobile barrier mechanism for cation-coupled symport.
- Published
- 2024
- Full Text
- View/download PDF
5. An Amphiphilic Peptide Carrier for HCl Transport.
- Author
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Kar, Sabnam and Madhavan, Nandita
- Subjects
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PEPTIDES , *SINGLE molecules , *MEMBRANE lipids , *CARBOXYLIC acids , *PROTON transfer reactions , *MONOCARBOXYLATE transporters - Abstract
Single molecules that co‐transport cations as well as anions across lipid membranes are few despite their high biological utility. The elegant yet simple lipidomimmetic peptide design herein enables efficient HCl transport without the use of any external additives for proton transport. The carboxylic acids in the dipeptide scaffold provide a handle to append two long hydrophobic tails and also provide a polar hydrophilic carboxylate group. The peptide central unit also provides NH sites for anion binding. Protonation of the carboxylate group coupled with the weak halide binding of the terminal NH group results in HCl transport with transport rates of H+>Cl−. The lipid‐like structure also facilitates seamless membrane integration and flipping of the molecule. The biocompatibility, design simplicity, and potential pH regulation of these molecules open up several avenues for their therapeutic use. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
6. Carbohydrate Transport—‘Life’s Useful Luxury Distributed’
- Author
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Steinberg, Christian E. W. and Steinberg, Christian E.W.
- Published
- 2022
- Full Text
- View/download PDF
7. Lactose Permease Scrambles Phospholipids
- Author
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Lei Wang and Peter Bütikofer
- Subjects
LacY ,scramblase ,phospholipids ,bilayer ,symporter ,Biology (General) ,QH301-705.5 - Abstract
Lactose permease (LacY) from Escherichia coli belongs to the major facilitator superfamily. It facilitates the co-transport of β-galactosides, including lactose, into cells by using a proton gradient towards the cell. We now show that LacY is capable of scrambling glycerophospholipids across a membrane. We found that purified LacY reconstituted into liposomes at various protein to lipid ratios catalyzed the rapid translocation of fluorescently labeled and radiolabeled glycerophospholipids across the proteoliposome membrane bilayer. The use of LacY mutant proteins unable to transport lactose revealed that glycerophospholipid scrambling was independent of H+/lactose transport activity. Unexpectedly, in a LacY double mutant locked into an occluded conformation glycerophospholipid, scrambling activity was largely inhibited. The corresponding single mutants revealed the importance of amino acids G46 and G262 for glycerophospholipid scrambling of LacY.
- Published
- 2023
- Full Text
- View/download PDF
8. Active site voltage clamp fluorometry of the sodium glucose cotransporter hSGLT1
- Author
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Gorraitz, Edurne, Hirayama, Bruce A, Paz, Aviv, Wright, Ernest M, and Loo, Donald DF
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Biochemistry and Cell Biology ,Medical Physiology ,Biomedical and Clinical Sciences ,Biological Sciences ,Generic health relevance ,Animals ,Binding Sites ,Catalytic Domain ,Cysteine ,Fluorometry ,Gene Expression ,Glucose ,Ions ,Models ,Animal ,Models ,Molecular ,Molecular Probe Techniques ,Mutation ,Oocytes ,Patch-Clamp Techniques ,Polyethylene Glycols ,Protein Conformation ,Rhodamines ,Sodium ,Sodium-Glucose Transporter 1 ,Symporters ,Xenopus laevis ,symporter ,active site ,conformation ,voltage ,tetramethylrhodamine - Abstract
In the human sodium glucose cotransporter (hSGLT1) cycle, the protein undergoes conformational changes where the sugar-binding site alternatively faces the external and internal surfaces. Functional site-directed fluorometry was used to probe the conformational changes at the sugar-binding site. Residues (Y290, T287, H83, and N78) were mutated to cysteines. The mutants were expressed in Xenopus laevis oocytes and tagged with environmentally sensitive fluorescent rhodamines [e.g., tetramethylrhodamine (TMR)-thiols]. The fluorescence intensity was recorded as the mutants were driven into different conformations using voltage jumps. Sugar binding and transport by the fluorophore-tagged mutants were blocked, but Na+ binding and the voltage-dependent conformational transitions were unaffected. Structural models indicated that external Na+ binding opened a large aqueous vestibule (600 Å3) leading to the sugar-binding site. The fluorescence of TMR covalently linked to Y290C, T287C, and H83C decreased as the mutant proteins were driven from the inward to the outward open Na+-bound conformation. The time courses of fluorescence changes (milliseconds) were close to the SGLT1 capacitive charge movements. The quench in rhodamine fluorescence indicated that the environment of the chromophores became more polar with opening of the external gates as the protein transitioned from the inward to outward facing state. Structural analyses showed an increase in polar side chains and a decrease in hydrophobic side chains lining the vestibule, and this was reflected in solvation of the chromophore. The results demonstrate the opening and closing of external gates in real time, with the accompanying changes of polarity of the sugar vestibule.
- Published
- 2017
9. Stochastic steps in secondary active sugar transport.
- Author
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Adelman, Joshua, Ghezzi, Chiara, Bisignano, Paola, Loo, Donald, Choe, Seungho, Abramson, Jeff, Rosenberg, John, Wright, Ernest, and Grabe, Michael
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SGLT ,kinetics ,simulation ,symporter ,transporter ,Glucose ,HEK293 Cells ,Humans ,Markov Chains ,Molecular Dynamics Simulation ,Monte Carlo Method ,Patch-Clamp Techniques ,Sodium ,Sodium-Glucose Transporter 1 - Abstract
Secondary active transporters, such as those that adopt the leucine-transporter fold, are found in all domains of life, and they have the unique capability of harnessing the energy stored in ion gradients to accumulate small molecules essential for life as well as expel toxic and harmful compounds. How these proteins couple ion binding and transport to the concomitant flow of substrates is a fundamental structural and biophysical question that is beginning to be answered at the atomistic level with the advent of high-resolution structures of transporters in different structural states. Nonetheless, the dynamic character of the transporters, such as ion/substrate binding order and how binding triggers conformational change, is not revealed from static structures, yet it is critical to understanding their function. Here, we report a series of molecular simulations carried out on the sugar transporter vSGLT that lend insight into how substrate and ions are released from the inward-facing state of the transporter. Our simulations reveal that the order of release is stochastic. Functional experiments were designed to test this prediction on the human homolog, hSGLT1, and we also found that cytoplasmic release is not ordered, but we confirmed that substrate and ion binding from the extracellular space is ordered. Our findings unify conflicting published results concerning cytoplasmic release of ions and substrate and hint at the possibility that other transporters in the superfamily may lack coordination between ions and substrate in the inward-facing state.
- Published
- 2016
10. Induced fit, ensemble binding space docking and Monte Carlo simulations of MDMA ‘ecstasy’ and 3D pharmacophore design of MDMA derivatives on the human serotonin transporter (hSERT)
- Author
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Ángel A. Islas, Laura G. Moreno, and Thomas Scior
- Subjects
Entactogen ,Psychoactive ,MDA ,MDAI ,Symporter ,Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
The popular recreational drug MDMA (3,4-methylenedioxy-methamphetamine) has a documented potential as a psychopharmacological clinical and research tool. This is due to its unique ability to promote reprocessing of traumatic memories, empathetic and pro-social states. Although it is established that MDMA exerts its behavioural effects via the serotonin transporter (SERT), the ligand-protein molecular interplay remains elusive. In order to shed light on the binding of MDMA and its primary congeneric entactogens (MDA, MBDB and MDAI), we first combined induced fit with Monte Carlo simulations. The computed interaction energies of the models correlated well with experimental activities (adjR2 = 0.78). Then we carried out ‘ensemble binding space docking’ on trajectories generated by interpolation of experimentally derived structures of the hSERT from the outward-open, and the occluded, to the inward-open states. This approach revealed low-energy alternative binding modes, suggesting high occupancy of the central site, yet considerable MDMA mobility within it, favouring the paroxetine-like orientation. Finally, we designed a pharmacophore that may be used to recognise hSERT-mediated serotonin releasers and uptake inhibitors of diverse chemical structure, identifying their active conformations and interacting residues. We conclude that the conserved amine-Asp98 ionic and edge-to-face π-π interactions are crucial to the mode of action of MDMA on the hSERT, underscoring the contributions of Tyr95 and gating residues Phe341, Tyr176 and Phe335. Amenable to experimental testing, our modelling may aid the rational design of novel entactogenic compounds and contribute to the understanding of an action mechanism, common and typical of psychotropic agents.
- Published
- 2021
- Full Text
- View/download PDF
11. Mobile barrier mechanisms for Na + -coupled symport in an MFS sugar transporter.
- Author
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Hariharan P, Shi Y, Katsube S, Willibal K, Burrows ND, Mitchell P, Bakhtiiari A, Stanfield S, Pardon E, Kaback HR, Liang R, Steyaert J, Viner R, and Guan L
- Subjects
- Ion Transport, Cations, Sugars, Membrane Transport Proteins, Sodium Chloride
- Abstract
While many 3D structures of cation-coupled transporters have been determined, the mechanistic details governing the obligatory coupling and functional regulations still remain elusive. The bacterial melibiose transporter (MelB) is a prototype of major facilitator superfamily transporters. With a conformation-selective nanobody, we determined a low-sugar affinity inward-facing Na
+ -bound cryoEM structure. The available outward-facing sugar-bound structures showed that the N- and C-terminal residues of the inner barrier contribute to the sugar selectivity. The inward-open conformation shows that the sugar selectivity pocket is also broken when the inner barrier is broken. Isothermal titration calorimetry measurements revealed that this inward-facing conformation trapped by this nanobody exhibited a greatly decreased sugar-binding affinity, suggesting the mechanisms for substrate intracellular release and accumulation. While the inner/outer barrier shift directly regulates the sugar-binding affinity, it has little or no effect on the cation binding, which is supported by molecular dynamics simulations. Furthermore, the hydron/deuterium exchange mass spectrometry analyses allowed us to identify dynamic regions; some regions are involved in the functionally important inner barrier-specific salt-bridge network, which indicates their critical roles in the barrier switching mechanisms for transport. These complementary results provided structural and dynamic insights into the mobile barrier mechanism for cation-coupled symport., Competing Interests: PH, SK, KW, NB, PM, AB, SS, EP, HK, RL, JS, LG No competing interests declared, YS, RV employee of Thermo Fisher Scientific, (© 2023, Hariharan et al.)- Published
- 2024
- Full Text
- View/download PDF
12. Transporters of glucose and other carbohydrates in bacteria.
- Author
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Jeckelmann, Jean-Marc and Erni, Bernhard
- Subjects
- *
MONOSACCHARIDES , *GLUCOSE transporters , *CARBOHYDRATES , *FORCE & energy , *SUGAR , *BIOLOGICAL transport , *FRUCTOSE , *ATP-binding cassette transporters - Abstract
Glucose arguably is the most important energy carrier, carbon source for metabolites and building block for biopolymers in all kingdoms of life. The proper function of animal organs and tissues depends on the continuous supply of glucose from the bloodstream. Most animals can resorb only a small number of monosaccharides, mostly glucose, galactose and fructose, while all other sugars oligosaccharides and dietary fibers are degraded and metabolized by the microbiota of the lower intestine. Bacteria, in contrast, are omnivorous. They can import and metabolize structurally different sugars and, as a consortium of different species, utilize almost any sugar, sugar derivative and oligosaccharide occurring in nature. Bacteria have membrane transport systems for the uptake of sugars against steep concentration gradients energized by ATP, the proton motive force and the high energy glycolytic intermediate phosphoenolpyruvate (PEP). Different uptake mechanisms and the broad range of overlapping substrate specificities allow bacteria to quickly adapt to and colonize changing environments. Here, we review the structures and mechanisms of bacterial representatives of (i) ATP-dependent cassette (ABC) transporters, (ii) major facilitator (MFS) superfamily proton symporters, (iii) sodium solute symporters (SSS) and (iv) enzyme II integral membrane subunits of the bacterial PEP-dependent phosphotransferase system (PTS). We give a short overview on the distribution of transporter genes and their phylogenetic relationship in different bacterial species. Some sugar transporters are hijacked for import of bacteriophage DNA and antibacterial toxins (bacteriocins) and they facilitate the penetration of polar antibiotics. Finally, we describe how the expression and activity of certain sugar transporters are controlled in response to the availability of sugars and how the presence and uptake of sugars may affect pathogenicity and host-microbiota interactions. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
13. Brief Report: A Novel Sodium/Iodide Symporter Mutation, S356F, Causing Congenital Hypothyroidism
- Author
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Harsh Durgia, Sadishkumar Kamalanathan, Erik Schoenmakers, Dhanapathi Halanaik, Jennifer A. Dickens, Jayaprakash Sahoo, Adeline K Nicholas, Nadia Schoenmakers, Sahoo, Jayaprakash [0000-0002-8805-143X], and Apollo - University of Cambridge Repository
- Subjects
Sodium-iodide symporter ,endocrine system ,medicine.medical_specialty ,dyshormonogenesis ,iodide transport ,endocrine system diseases ,Endocrinology, Diabetes and Metabolism ,India ,medicine.disease_cause ,Follicular cell ,SLC5A5 ,Endocrinology ,Mutant protein ,Internal medicine ,Congenital Hypothyroidism ,medicine ,Humans ,Iodide transport ,health care economics and organizations ,Mutation ,Symporters ,business.industry ,Thyroid ,Infant, Newborn ,medicine.disease ,Congenital hypothyroidism ,medicine.anatomical_structure ,Symporter ,Female ,business - Abstract
The sodium-iodide symporter (NIS, SLC5A5) is expressed at the basolateral membrane of the thyroid follicular cell, and facilitates the thyroidal iodide uptake required for thyroid hormone biosynthesis. Biallelic loss-of-function mutations in NIS are a rare cause of dyshormonogenic congenital hypothyroidism. Affected individuals typically exhibit a normally sited, often goitrous thyroid gland, with absent uptake of radioiodine in the thyroid and other NIS-expressing tissues. We report a novel homozygous NIS mutation (c.1067 C>T, p.S356F) in four siblings from a consanguineous Indian kindred, presenting with significant hypothyroidism. Functional characterization of the mutant protein demonstrated impaired plasma membrane localization and cellular iodide transport.
- Published
- 2022
14. Low-Iodine Diet of 4 Days Is Sufficient Preparation for I-131 Therapy in Differentiated Thyroid Cancer Patients
- Author
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Judith A P Bons, Adrienne H. Brouwers, Mirthe H Links, Linda G Swart-Busscher, Anneke C. Muller Kobold, Bernadette L Dekker, Thera P. Links, Marleen Kars, Anouk N A van der Horst-Schrivers, Interne Geneeskunde, MUMC+: MA Endocrinologie (9), MUMC+: DA CDL Algemeen (9), RS: NUTRIM - R3 - Respiratory & Age-related Health, Guided Treatment in Optimal Selected Cancer Patients (GUTS), Basic and Translational Research and Imaging Methodology Development in Groningen (BRIDGE), and Damage and Repair in Cancer Development and Cancer Treatment (DARE)
- Subjects
Male ,Calorie ,SYMPORTER ,Endocrinology, Diabetes and Metabolism ,Clinical Biochemistry ,Urine ,REEVALUATION ,Biochemistry ,Gastroenterology ,ABLATION THERAPY ,Iodine Radioisotopes ,Endocrinology ,low-iodine diet ,ASSOCIATION GUIDELINES ,Prospective Studies ,Prospective cohort study ,Thyroid cancer ,individual perceptions ,urinary iodine excretion ,OUTPATIENT PREPARATION ,Radioiodine therapy ,Middle Aged ,radioactive iodine therapy ,Diet Records ,iodine intake ,EXPERIENCES ,Female ,AcademicSubjects/MED00250 ,Iodine ,Adult ,medicine.medical_specialty ,nutrition diary ,chemistry.chemical_element ,Nutritional Status ,Context (language use) ,Excretion ,SEVERE HYPONATREMIA ,Internal medicine ,medicine ,MANAGEMENT ,Humans ,Thyroid Neoplasms ,Online Only Articles ,Clinical Research Articles ,Aged ,business.industry ,Biochemistry (medical) ,medicine.disease ,Diet ,Trace Elements ,chemistry ,business - Abstract
Context No consensus exists about the optimal duration of the low-iodine diet (LID) in the preparation of 131I therapy in differentiated thyroid cancer (DTC) patients. Objective This work aimed to investigate if a LID of 4 days is enough to achieve adequate iodine depletion in preparation for 131I therapy. In addition, the nutritional status of the LID was evaluated. Methods In this prospective study, 65 DTC patients treated at 2 university medical centers were included between 2018 and 2021. The patients collected 24-hour urine on days 4 and 7 of the LID and kept a food diary before and during the LID. The primary outcome was the difference between the 24-hour urinary iodine excretion (UIE) on both days. Results The median 24-hour UIE on days 4 and 7 of the LID were not significantly different (36.1 mcg [interquartile range, 25.4-51.2 mcg] and 36.5 mcg [interquartile range, 23.9-47.7 mcg], respectively, P = .43). On day 4 of the LID, 72.1% of the DTC patients were adequately prepared (24-hour UIE Conclusion The 24-hour UIE on day 4 of the LID did not differ from day 7, and therefore shortening the LID from 7 to 4 days seems justified to prepare DTC patients for 131I therapy in areas with sufficient iodine intake and may be beneficial to maintain a sufficient nutritional intake during DTC treatment.
- Published
- 2022
15. Monodirectional Evolutional Symport Tissue P Systems With Promoters and Cell Division
- Author
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Kenli Li, Bosheng Song, and Xiangxiang Zeng
- Subjects
Computational Theory and Mathematics ,Cell division ,Hardware and Architecture ,Computer science ,Signal Processing ,Symporter ,Theory of computation ,Promoter ,Natural number ,Topology ,NP-complete - Abstract
Monodirectional tissue P systems with promoters are natural inspired parallel computing paradigms, where only symport rules are permitted, and with the restriction of “monodirectionality”, objects for two given regions are transferred in one direction. In this article, a novel kind of P systems, monodirectional evolutional symport tissue P systems with promoters (MESTP P systems) is raised, where objects may be revised during the movement between two regions. The computational theory of MESTP P systems that rules are employed in a flat maximally parallel pattern is investigated. We prove that finite natural number sets are created by MESTP P systems applying one cell, at most 1 promoter and all evolutional symport rules having a maximal length 2 or with arbitrary number of cells, promoters and all evolutional symport rules having a maximal length 2. MESTP P systems are Turing universal when two cells, at most 1 promoter and all evolutional symport rules having a maximal length 2 are employed. In addition, with the help of cell division mechanism, monodirectional evolutional symport tissue P systems with promoters and cell division (MESTPD P systems) are employed to solve NP -complete (the SAT ) problem, where system uses at most 1 promoter and all evolutional symport rules having a maximal length 3. These results show that MESTP(D) P systems are still computationally powerful even if monodirectionality control mechanism is imposed, thereby developing membrane algorithms for MESTP(D) P systems is theoretically possible as well as potentially exploitable.
- Published
- 2022
16. Structural and thermodynamic insights into a novel Mg2+–citrate-binding protein from the ABC transporter superfamily
- Author
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Suraj Kumar Mandal and Shankar Prasad Kanaujia
- Subjects
Biochemistry ,biology ,Structural Biology ,Cyclic nucleotide-binding domain ,Chemistry ,Binding protein ,Metal ions in aqueous solution ,Symporter ,ATP-binding cassette transporter ,Transporter ,Thermus thermophilus ,Ligand (biochemistry) ,biology.organism_classification - Abstract
More than one third of proteins require metal ions to accomplish their functions, making them obligatory for the growth and survival of microorganisms in varying environmental niches. In prokaryotes, besides their involvement in various cellular and physiological processes, metal ions stimulate the uptake of citrate molecules. Citrate is a source of carbon and energy and is reported to be transported by secondary transporters. In Gram-positive bacteria, citrate molecules are transported in complex with divalent metal ions, whereas in Gram-negative bacteria they are translocated by Na+/citrate symporters. In this study, the presence of a novel divalent-metal-ion-complexed citrate-uptake system that belongs to the primary active ABC transporter superfamily is reported. For uptake, the metal-ion-complexed citrate molecules are sequestered by substrate-binding proteins (SBPs) and transferred to transmembrane domains for their transport. This study reports crystal structures of an Mg2+–citrate-binding protein (MctA) from the Gram-negative thermophilic bacterium Thermus thermophilus HB8 in both apo and holo forms in the resolution range 1.63–2.50 Å. Despite binding various divalent metal ions, MctA possesses the coordination geometry to bind its physiological metal ion, Mg2+. The results also suggest an extended subclassification of cluster D SBPs, which are known to bind and transport divalent-metal-ion-complexed citrate molecules. Comparative assessment of the open and closed conformations of the wild-type and mutant MctA proteins suggests a gating mechanism of ligand entry following an `asymmetric domain movement' of the N-terminal domain for substrate binding.
- Published
- 2021
17. Thermostability-based binding assays reveal complex interplay of cation, substrate and lipid binding in the bacterial DASS transporter, VcINDY
- Author
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Connor D.D. Sampson, Christopher Mulligan, Cristina Fabregas Bellavista, and Matthew J Stewart
- Subjects
Biophysics ,membrane proteins ,Biochemistry ,Divalent ,lipids ,Cations ,Binding site ,Molecular Biology ,Vibrio cholerae ,Research Articles ,Thermostability ,Sodium Sulfate Cotransporter ,chemistry.chemical_classification ,Binding Sites ,Molecular Interactions ,Substrate (chemistry) ,Transporter ,Cell Biology ,Ligand (biochemistry) ,Lipid Metabolism ,chemistry ,Membrane protein ,membranes ,Symporter ,transport ,Cell Membranes, Excitation & Transport ,QP517 ,Protein Binding - Abstract
The divalent anion sodium symporter (DASS) family of transporters (SLC13 family in humans) are key regulators of metabolic homeostasis, disruption of which results in protection from diabetes and obesity, and inhibition of liver cancer cell proliferation. Thus, DASS transporter inhibitors are attractive targets in the treatment of chronic, age-related metabolic diseases. The characterisation of several DASS transporters has revealed variation in the substrate selectivity and flexibility in the coupling ion used to power transport. Here, using the model DASS co-transporter, VcINDY from Vibrio cholerae, we have examined the interplay of the three major interactions that occur during transport: the coupling ion, the substrate, and the lipid environment. Using a series of high-throughput thermostability-based interaction assays, we have shown that substrate binding is Na+-dependent; a requirement that is orchestrated through a combination of electrostatic attraction and Na+-induced priming of the binding site architecture. We have identified novel DASS ligands and revealed that ligand binding is dominated by the requirement of two carboxylate groups in the ligand that are precisely distanced to satisfy carboxylate interaction regions of the substrate-binding site. We have also identified a complex relationship between substrate and lipid interactions, which suggests a dynamic, regulatory role for lipids in VcINDY's transport cycle.
- Published
- 2021
18. Capsaicin restores sodium iodine symporter-mediated radioiodine uptake through bypassing canonical TSH‒TSHR pathway in anaplastic thyroid carcinoma cells
- Author
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Yunping Wang, Jing Wu, Jiandong Bao, Liying Wu, Li Zhang, Xian Cheng, Shichen Xu, Huixin Yu, and Xiaowen Wang
- Subjects
CAMP Responsive Element Binding Protein ,Cellular differentiation ,Thyrotropin ,CREB ,AcademicSubjects/SCI01180 ,Thyroid Carcinoma, Anaplastic ,capsaicin ,Iodine Radioisotopes ,chemistry.chemical_compound ,Thyroid peroxidase ,Cell Line, Tumor ,Genetics ,medicine ,Humans ,Cyclic adenosine monophosphate ,Thyroid Neoplasms ,Anaplastic thyroid cancer ,Molecular Biology ,biology ,Symporters ,Chemistry ,Sodium ,anaplastic thyroid carcinoma ,Receptors, Thyrotropin ,Cell Biology ,General Medicine ,Articles ,medicine.disease ,radioactive iodine therapy ,redifferentiation ,sodium iodine symporter ,Editor's Choice ,Symporter ,biology.protein ,Cancer research ,Signal transduction ,Iodine - Abstract
Anaplastic thyroid cancer (ATC) is a rare but highly lethal disease. ATCs are resistant to standard therapies and are extremely difficult to manage. The stepwise cell dedifferentiation results in the impairment of the iodine-metabolizing machinery and the infeasibility of radioiodine treatment in ATC. Hence, reinducing iodine-metabolizing gene expression to restore radioiodine avidity is considered as a promising strategy to fight against ATC. In the present study, capsaicin (CAP), a natural potent transient receptor potential vanilloid type 1 (TRPV1) agonist, was discovered to reinduce ATC cell differentiation and to increase the expression of thyroid transcription factors (TTFs including TTF-1, TTF-2, and PAX8) and iodine-metabolizing proteins, including thyroid-stimulating hormone receptor (TSHR), thyroid peroxidase, and sodium iodine symporter (NIS), in two ATC cell lines, 8505C and FRO. Strikingly, CAP treatment promoted NIS glycosylation and its membrane trafficking, resulting in a significant enhancement of radioiodine uptake of ATC cells in vitro. Mechanistically, CAP-activated TRPV1 channel and subsequently triggered Ca2+ influx, cyclic adenosine monophosphate (cAMP) generation, and cAMP-responsive element-binding protein (CREB) signal activation. Next, CREB recognized and bound to the promoter of SLC5A5 to facilitate its transcription. Moreover, the TRPV1 antagonist CPZ, the calcium chelator BAPTA, and the PKA inhibitor H-89 effectively alleviated the redifferentiation exerted by CAP, demonstrating that CAP might improve radioiodine avidity through the activation of the TRPV1‒Ca2+/cAMP/PKA/CREB signaling pathway. In addition, our study indicated that CAP might trigger a novel cascade to redifferentiate ATC cells and provide unprecedented opportunities for radioiodine therapy in ATC, bypassing canonical TSH‒TSHR pathway.
- Published
- 2021
19. Amino Acid Transport Defects in Human Inherited Metabolic Disorders
- Author
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Raquel Yahyaoui and Javier Pérez-Frías
- Subjects
slc ,solute carriers ,membrane transport ,inborn errors of metabolism ,amino acid transporter ,symporter ,inherited metabolic disorders ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Amino acid transporters play very important roles in nutrient uptake, neurotransmitter recycling, protein synthesis, gene expression, cell redox balance, cell signaling, and regulation of cell volume. With regard to transporters that are closely connected to metabolism, amino acid transporter-associated diseases are linked to metabolic disorders, particularly when they involve different organs, cell types, or cell compartments. To date, 65 different human solute carrier (SLC) families and more than 400 transporter genes have been identified, including 11 that are known to include amino acid transporters. This review intends to summarize and update all the conditions in which a strong association has been found between an amino acid transporter and an inherited metabolic disorder. Many of these inherited disorders have been identified in recent years. In this work, the physiological functions of amino acid transporters will be described by the inherited diseases that arise from transporter impairment. The pathogenesis, clinical phenotype, laboratory findings, diagnosis, genetics, and treatment of these disorders are also briefly described. Appropriate clinical and diagnostic characterization of the underlying molecular defect may give patients the opportunity to avail themselves of appropriate therapeutic options in the future.
- Published
- 2019
- Full Text
- View/download PDF
20. Solving a PSPACE-complete problem by symport/antiport P systems with promoters and membrane division
- Author
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Xiangxiang Zeng and Bosheng Song
- Subjects
Discrete mathematics ,Membrane ,Computational Theory and Mathematics ,Applied Mathematics ,Antiporter ,Symporter ,Theory of computation ,Division (mathematics) ,PSPACE-complete ,Time complexity ,Mathematics - Abstract
Symport/antiport P systems with membrane division are parallel computing models, which can solve NP-complete problems in polynomial time. In this paper, promoters are incorporated into symport/antiport P systems with membrane division, and a new kind of P systems, called symport/antiport P systems with promoters and membrane division (SAPD P systems, for short) is proposed. The computational efficiency of SAPD P systems is investigated. We show that a uniform solution to the QSAT problem is given by using only symport rules of length at most 2 and promoters of length at most 1 in a polynomial time (Note that the QSAT problem can be solved by symport/antiport P systems with membrane division using both symport rules and antiport rules of length at most 3 (Song et al. in BioSystems 130: 51–58, 2015)).
- Published
- 2021
21. Na+/I− symporter expression, function, and regulation in non-thyroidal tissues and impact on thyroid cancer therapy
- Author
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Jennifer A. Sipos and Sissy M. Jhiang
- Subjects
Cancer Research ,Symporters ,business.industry ,Endocrinology, Diabetes and Metabolism ,Thyroid ,medicine.disease ,Article ,Iodine Radioisotopes ,Endocrinology ,Nasolacrimal duct obstruction ,medicine.anatomical_structure ,Oncology ,Lacrimal Duct Obstruction ,Symporter ,medicine ,Cancer research ,Humans ,Thyroid Neoplasms ,Adverse effect ,Prospective cohort study ,business ,Nasolacrimal Duct ,Thyroid cancer ,Pathological ,Function (biology) - Abstract
For the past 80 years, radioiodine (131I) has been used to ablate thyroid tissue not removed by surgery or to treat differentiated thyroid cancer that has metastasized to other parts of the body. However, the Na+/I− symporter (NIS), which mediates active iodide uptake into thyroid follicular cells, is also expressed in several non-thyroidal tissues. This NIS expression permits 131I accumulation and radiation damage in these non-target tissues, which accounts for the adverse effects of radioiodine therapy. We will review the data regarding the expression, function, and regulation of NIS in non-thyroidal tissues and explain the seemingly paradoxical adverse effects induced by 131I, the self-limited gastrointestinal adverse effects in contrast to the permanent salivary dysfunction that is seen after 131I therapy. We propose that prospective studies are needed to uncover the time-course of pathological processes underlying development and progression or ultimate resolution of 131I-induced salivary ductal obstruction and nasolacrimal duct obstruction. Finally, preventive measures and early therapeutic interventions that can be applied potentially to eliminate or alleviate long-term radioiodine adverse effects will be discussed.
- Published
- 2021
22. The ups and downs of elevator‐type di‐/tricarboxylate membrane transporters
- Author
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Da-Neng Wang, William J. Rice, Jinmei Song, Bing Wang, David B. Sauer, Joseph C Sudar, and Jennifer Marden
- Subjects
Anions ,Dicarboxylic Acid Transporters ,chemistry.chemical_classification ,Symporters ,Structural similarity ,Sodium ,Membrane Transport Proteins ,Transporter ,Cell Biology ,Biochemistry ,Tricarboxylate ,Article ,Divalent ,Protein structure ,chemistry ,Symporter ,Humans ,Cotransporter ,Molecular Biology ,Ion transporter - Abstract
The divalent anion sodium symporter (DASS) family contains both sodium-driven anion co-transporters and anion/anion exchangers. The family belongs to a broader Ion Transporter Superfamily (ITS), which comprises 24 families of transporters, including those of AbgT antibiotic efflux transporters. The human proteins in the DASS family play major physiological roles and are drug targets. We recently determined multiple structures of the human sodium-dependent citrate transporter (NaCT) and the succinate/dicarboxylate transporter from Lactobacillus acidophilus (LaINDY). Structures of both proteins show high degrees of structural similarity to the previously-determined VcINDY fold. Conservation between these DASS protein structures and those from the AbgT familiy indicates that the VcINDY fold represents the overall protein structure for the entire ITS superfamily. The new structures of NaCT and LaINDY are captured in the inward- or outward-facing conformations, respectively. The domain arrangements in these structures agree with a rigid-body elevator-type transport mechanism for substrate translocation across the membrane. Two separate NaCT structures in complex with a substrate or an inhibitor allowed us to explain the inhibition mechanism and propose a detailed classification scheme for grouping disease-causing mutations in the human protein. Structural understanding of multiple kinetic states of DASS proteins is a first step towards the detailed characterization of their entire transport cycle.
- Published
- 2021
23. Analysis of L-leucine amino acid transporter species activity and gene expression by human blood brain barrier hCMEC/D3 model reveal potential LAT1, LAT4, B0AT2 and y+LAT1 functional cooperation
- Author
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Mehdi Taslimifar, Martin Faltys, Victoria Makrides, François Verrey, Vartan Kurtcuoglu, University of Zurich, and Makrides, Victoria
- Subjects
congenital, hereditary, and neonatal diseases and abnormalities ,insulin-like growth factor 1 ,Fusion Regulatory Protein 1, Heavy Chain ,Models, Neurological ,Nerve Tissue Proteins ,610 Medicine & health ,hCMEC/D3 ,Blood–brain barrier ,2705 Cardiology and Cardiovascular Medicine ,Cell Line ,Large Neutral Amino Acid-Transporter 1 ,10052 Institute of Physiology ,Leucine ,medicine ,Humans ,Amino acid transporter ,Receptor ,chemistry.chemical_classification ,Amino Acid Transport System y+L ,Endothelial Cells ,Transporter ,Original Articles ,Cell biology ,Amino acid ,Solute carrier family ,computational model ,Amino Acid Transport Systems, Neutral ,2728 Neurology (clinical) ,medicine.anatomical_structure ,Gene Expression Regulation ,Neurology ,chemistry ,Blood-Brain Barrier ,2808 Neurology ,Symporter ,solute carrier amino acid transporters ,570 Life sciences ,biology ,Neurology (clinical) ,Cardiology and Cardiovascular Medicine - Abstract
In the CNS, amino acid (AA) neurotransmitters and neurotransmitter precursors are subject to tight homeostatic control mediated by blood-brain barrier (BBB) solute carrier amino acid transporters (AATs). Since the BBB is composed of multiple closely apposed cell types and opportunities for human in vivo studies are limited, we used in vitro and computational approaches to investigate human BBB AAT activity and regulation. Quantitative real-time PCR (qPCR) of the human BBB endothelial cell model hCMEC/D3 (D3) was used to determine expression of selected AAT, tight junction (TJ), and signal transduction (ST) genes under various culture conditions. L-leucine uptake data were interrogated with a computational model developed by our group for calculating AAT activity in complex cell cultures. This approach is potentially applicable to in vitro cell culture drug studies where multiple “receptors” may mediate observed responses. Of 7 Leu AAT genes expressed by D3 only the activity of SLC7A5-SLC3A2/LAT1-4F2HC (LAT1), SLC43A2/LAT4 (LAT4) and sodium-dependent AATs, SLC6A15/B0AT2 (B0AT2), and SLC7A7/y+LAT1 (y+LAT1) were calculated to be required for Leu uptake. Therefore, D3 Leu transport may be mediated by a potentially physiologically relevant functional cooperation between the known BBB AAT, LAT1 and obligatory exchange (y+LAT1), facilitative diffusion (LAT4), and sodium symporter (B0AT2) transporters.
- Published
- 2021
24. Impact of natural mutations on the riboflavin transporter 2 and their relevance to human riboflavin transporter deficiency 2
- Author
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Lara Console, Jessica Cosco, Cesare Indiveri, Maria Barile, Maria Tolomeo, and Keith Massey
- Subjects
biology ,Chemistry ,Hearing Loss, Sensorineural ,Clinical Biochemistry ,Mutant ,Glucose transporter ,Neurodegenerative Diseases ,Riboflavin ,Transporter ,Cell Biology ,Equilibrative nucleoside transporter 1 ,Biochemistry ,Receptors, G-Protein-Coupled ,Transport protein ,Solute carrier family ,Mutation ,Symporter ,Genetics ,biology.protein ,Humans ,Molecular Biology - Abstract
Riboflavin transporter deficiency 2 (RTD2) is a rare neurological disorder caused by mutations in the Solute carrier family 52 member 2 (Slc52a2) gene encoding human riboflavin transporter 2 (RFVT2). This transporter is ubiquitously expressed and mediates tissue distribution of riboflavin, a water-soluble vitamin that, after conversion into FMN and FAD, plays pivotal roles in carbohydrate, protein, and lipid metabolism. The 3D structure of RFVT2 has been constructed by homology modeling using three different templates that are equilibrative nucleoside transporter 1 (ENT1), Fucose: proton symporter, and glucose transporter type 5 (GLUT5). The structure has been validated by several approaches. All known point mutations of RFVT2, associated with RTD2, have been localized in the protein 3D model. Six of these mutations have been introduced in the recombinant protein for functional characterization. The mutants W31S, S52F, S128L, L312P, C325G, and M423V have been expressed in E. coli, purified, and reconstituted into proteoliposomes for transport assay. All the mutants showed impairment of function. The Km for riboflavin of the mutants increased from about 3 to 9 times with respect to that of WT, whereas Vmax was only marginally affected. This agrees with the improved outcome of most RTD2 patients after administration of high doses of riboflavin.
- Published
- 2021
25. Regulation of the Tpo , Tg , Duox2 , Pds , and Mct8 genes involved in the synthesis of thyroid hormones after subchronic exposure to sodium nitrate in female Wistar rats
- Author
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María Eugenia Gonsebatt Bonaparte, E Rios-Sanchez, Alberto González-Zamora, María Fernanda González-Delgado, Rebeca Pérez-Morales, Alejandra Zámago Amaro, and Elizabeth Meza Mata
- Subjects
endocrine system ,medicine.medical_specialty ,biology ,Chemistry ,Health, Toxicology and Mutagenesis ,Thyroid ,Dual oxidase 2 ,General Medicine ,Pendrin ,Management, Monitoring, Policy and Law ,Toxicology ,Endocrinology ,medicine.anatomical_structure ,Thyroid peroxidase ,Internal medicine ,Symporter ,medicine ,biology.protein ,Endocrine system ,Receptor ,Hormone - Abstract
Nitrates are natural compounds present in soil and water; however, the intense use of fertilizers has increased their presence in groundwater with deleterious effects on human health. There is evidence of nitrates acting as endocrine disruptors; however, the underlying molecular mechanisms have not been fully described. Here, we investigated the effect of subchronic exposure to different concentrations of sodium nitrate in female Wistar rats, evaluating thyroid hormonal parameters, such as Nis transporter (Na+ /I- symporter, Slc5a5) and Tsh-R receptor protein expression, as well as transcription of the Tpo (thyroperoxidase), Tg (tiroglobulin), Duox2 (dual oxidase 2), Pds (pendrin), and Mct8 (Mct8 transporter, Slc16a2) genes. Hematological and histochemical changes in the liver and thyroid were also explored. Significant differences were found in platelet and leukocyte counts; although a significant increase in the weight of the thyroid gland was observed, no differences were found in the levels of the hormones Tsh, T3, and T4, but a modulation of the mRNA expression of the Tg, Tpo, Duox2, Mct8, and Pds genes was observed. Morphological changes were also found in liver and thyroid tissue according to the exposure doses. In conclusion, subchronic exposure to sodium nitrate induces leukocytosis consistent with an inflammatory response and upregulation of Sod2 in the liver and increases the expression of genes involved in the synthesis of thyroid hormones, keeping thyroid hormone levels stable. Histological changes in the thyroid gland suggest a goitrogenic effect.
- Published
- 2021
26. Elucidating the Mechanism Behind Sodium-Coupled Neurotransmitter Transporters by Reconstitution
- Author
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Ulrik Gether, Solveig G. Schmidt, and Claus J. Loland
- Subjects
chemistry.chemical_classification ,Neurotransmitter transporter ,Mechanism (biology) ,Transporter ,General Medicine ,Membrane transport ,Biochemistry ,Amino acid ,Cell biology ,Cellular and Molecular Neuroscience ,chemistry.chemical_compound ,chemistry ,Symporter ,Excitatory postsynaptic potential ,Neurotransmitter - Abstract
Sodium-coupled neurotransmitter transporters play a fundamental role in the termination of synaptic neurotransmission, which makes them a major drug target. The reconstitution of these secondary active transporters into liposomes has shed light on their molecular transport mechanisms. From the earliest days of the reconstitution technique up to today’s single-molecule studies, insights from live functioning transporters have been indispensable for our understanding of their physiological impact. The two classes of sodium-coupled neurotransmitter transporters, the neurotransmitter: sodium symporters and the excitatory amino acid transporters, have vastly different molecular structures, but complementary proteoliposome studies have sought to unravel their ion-dependence and transport kinetics. Furthermore, reconstitution experiments have been used on both protein classes to investigate the role of e.g. the lipid environment, of posttranslational modifications, and of specific amino acid residues in transport. Techniques that allow the detection of transport at a single-vesicle resolution have been developed, and single-molecule studies have started to reveal single transporter kinetics, which will expand our understanding of how transport across the membrane is facilitated at protein level. Here, we review a selection of the results and applications where the reconstitution of the two classes of neurotransmitter transporters has been instrumental.
- Published
- 2021
27. X-ray crystallography reveals molecular recognition mechanism for sugar binding in a melibiose transporter MelB
- Author
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Guan, Lan and Hariharan, Parameswaran
- Subjects
Salmonella typhimurium ,Stereochemistry ,QH301-705.5 ,Mutant ,Medicine (miscellaneous) ,Crystallography, X-Ray ,Article ,General Biochemistry, Genetics and Molecular Biology ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Molecular recognition ,Bacterial Proteins ,Biology (General) ,Melibiose ,X-ray crystallography ,030304 developmental biology ,0303 health sciences ,Symporters ,Ligand ,Chemistry ,Cooperative binding ,Transporter ,Major facilitator superfamily ,Symporter ,Permeation and transport ,General Agricultural and Biological Sciences ,030217 neurology & neurosurgery - Abstract
Major facilitator superfamily_2 transporters are widely found from bacteria to mammals. The melibiose transporter MelB, which catalyzes melibiose symport with either Na+, Li+, or H+, is a prototype of the Na+-coupled MFS transporters, but its sugar recognition mechanism has been a long-unsolved puzzle. Two high-resolution X-ray crystal structures of a Salmonella typhimurium MelB mutant with a bound ligand, either nitrophenyl-α-d-galactoside or dodecyl-β-d-melibioside, were refined to a resolution of 3.05 or 3.15 Å, respectively. In the substrate-binding site, the interaction of both galactosyl moieties on the two ligands with MelBSt are virturally same, so the sugar specificity determinant pocket can be recognized, and hence the molecular recognition mechanism for sugar binding in MelB has been deciphered. The conserved cation-binding pocket is also proposed, which directly connects to the sugar specificity pocket. These key structural findings have laid a solid foundation for our understanding of the cooperative binding and symport mechanisms in Na+-coupled MFS transporters, including eukaryotic transporters such as MFSD2A., Guan and Hariharan report two crystal structures of melibiose transporter MelB in complex with substrate analogs, nitrophenyl-galactoside, and dodecyl-melibioside. Both structures revealed similar specific site for sugar recognition and resolved the cation-binding pocket, advancing the understanding of MelB and related transporters.
- Published
- 2021
28. Symporter
- Author
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Wells, Robert D., editor, Bond, Judith S., editor, Klinman, Judith, editor, Masters, Bettie Sue Siler, editor, Bell, Ellis, Managing Editor, and Kaguni, Laurie S., Book Editor
- Published
- 2018
- Full Text
- View/download PDF
29. All-Atom Simulations Uncover the Molecular Terms of the NKCC1 Transport Mechanism
- Author
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Alessandra Magistrato and Pavel Janoš
- Subjects
Ion Transport ,Symporters ,Chemistry ,Mechanism (biology) ,General Chemical Engineering ,Sodium ,Biological Transport ,General Chemistry ,Library and Information Sciences ,Computer Science Applications ,Transepithelial water transport ,Membrane ,Order (biology) ,Symporter ,Biophysics ,Humans ,Solute Carrier Family 12, Member 2 ,Cotransporter ,Ion transporter ,Homeostasis - Abstract
The secondary-active Na-K-Cl cotransporter 1 (NKCC1), member of the cation-chloride cotransporter (CCC) family, ensures the electroneutral movement of Cl-, Na+, and K+ ions across cellular membranes. NKCC1 regulates Cl- homeostasis and cell volume, handling a pivotal role in transepithelial water transport and neuronal excitability. Aberrant NKCC1 transport is hence implicated in a variety of human diseases (hypertension, renal disorders, neuropathies, and cancer). Building on the newly resolved NKCC1 cryo-EM structure, all-atom enhanced sampling simulations unprecedentedly unlock the mechanism of NKCC1-mediated ion transport, assessing the order and the molecular basis of its interdependent ion translocation. Our outcomes strikingly advance the understanding of the physiological mechanism of CCCs and disclose a key role of CCC-conserved asparagine residues, whose side-chain promiscuity ensures the transport of both negatively and positively charged ions along the same translocation route. This study sets a conceptual basis to devise NKCC-selective inhibitors to treat diseases linked to Cl- dishomeostasis.
- Published
- 2021
30. A fructose/H+ symporter controlled by a LacI-type regulator promotes survival of pandemic Vibrio cholerae in seawater
- Author
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Qian Wang, Wendi Li, Tingting Xu, Ruiying Liu, Xi Guo, Yutao Liu, Lu Feng, Jialin Wu, Xiaoyu Zheng, Bin Liu, Xingmei Liu, and Lei Wang
- Subjects
Science ,General Physics and Astronomy ,Virulence ,medicine.disease_cause ,General Biochemistry, Genetics and Molecular Biology ,Microbiology ,03 medical and health sciences ,chemistry.chemical_compound ,medicine ,Pathogen ,030304 developmental biology ,0303 health sciences ,Multidisciplinary ,biology ,030306 microbiology ,Fructose ,General Chemistry ,PEP group translocation ,biology.organism_classification ,medicine.disease ,Cholera ,chemistry ,Vibrio cholerae ,Symporter ,Bacteria - Abstract
The bacterium Vibrio cholerae can colonize the human intestine and cause cholera, but spends much of its life cycle in seawater. The pathogen must adapt to substantial environmental changes when moving between seawater and the human intestine, including different availability of carbon sources such as fructose. Here, we use in vitro experiments as well as mouse intestinal colonization assays to study the mechanisms used by pandemic V. cholerae to adapt to these environmental changes. We show that a LacI-type regulator (FruI) and a fructose/H+ symporter (FruT) are important for fructose uptake at low fructose concentrations, as those found in seawater. FruT is downregulated by FruI, which is upregulated when O2 concentrations are low (as in the intestine) by ArcAB, a two-component system known to respond to changes in oxygen levels. As a result, the bacteria predominantly use FruT for fructose uptake under seawater conditions (low fructose, high O2), and use a known fructose phosphotransferase system (PTS, Fpr) for fructose uptake under conditions found in the intestine. PTS activity leads to reduced levels of intracellular cAMP, which in turn upregulate virulence genes. Our results indicate that the FruT/FruI system may be important for survival of pandemic V. cholerae in seawater.
- Published
- 2021
31. Testosterone is Sufficient to Impart Susceptibility to Isoflurane Neurotoxicity in Female Neonatal Rats
- Author
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Katrina Duong, Jeffrey W. Sall, Gregory A. Chinn, Jennifer M. Sasaki Russell, and Tal R Horovitz
- Subjects
medicine.medical_specialty ,business.industry ,Neurotoxicity ,Testosterone (patch) ,medicine.disease ,Barnes maze ,Anesthesiology and Pain Medicine ,Endocrinology ,Isoflurane ,Internal medicine ,Anesthetic ,Symporter ,medicine ,GABAergic ,Surgery ,Neurology (clinical) ,medicine.symptom ,business ,Cognitive deficit ,medicine.drug - Abstract
BACKGROUND Volatile anesthetic exposure during development leads to long-term cognitive deficits in rats which are dependent on age and sex. Female rats are protected relative to male rats for the same exposure on postnatal day 7. Here we test our hypothesis that androgens can modulate chloride cotransporter expression to alter the susceptibility to neurotoxicity from GABAergic drugs using female rats with exogenous testosterone exposure. METHODS Female rats were injected with testosterone (100 μg/animal) or vehicle on postnatal days 1 to 6. On postnatal day 7, the animals were randomized to either isoflurane exposure or sham. Spatial memory was assessed with the Barnes maze starting on postnatal day 41. Western blots were run from testosterone treated postnatal day 7 animals to measure levels of chloride cotransporters sodium-potassium-chloride symporter (NKCC1) and chloride-potassium symporter 5 (KCC2). RESULTS Exogenous testosterone modulated isoflurane anesthetic neurotoxicity in female rats based on poor performance in the probe trial of the Barnes Maze. By contrast, females with vehicle and isoflurane exposure were able to differentiate the goal position. These behavioral differences corresponded to differences in the protein levels of NKCC1 and KCC2 after exogenous testosterone exposure, with NKCC1 increasing (P
- Published
- 2021
32. Crown ether-thiourea conjugates as ion transporters
- Author
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Bailing Tang, Philip A. Gale, Zhao Li, Xin Wu, Xiao-Sheng Yan, Zhixing Zhao, and Yun-Bao Jiang
- Subjects
Membrane potential ,chemistry.chemical_classification ,010405 organic chemistry ,Chemistry ,General Chemical Engineering ,Vesicle ,0904 Chemical Engineering ,Synthetic membrane ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,ion transport ,symport ,Membrane ,crown ether ,0399 Other Chemical Sciences ,Symporter ,Biophysics ,Lipid bilayer ,thiourea ,Ion transporter ,Crown ether - Abstract
Na+, Cl− and K+ are the most abundant electrolytes present in biological fluids that are essential to the regulation of pH homeostasis, membrane potential and cell volume in living organisms. Herein, we report synthetic crown ether-thiourea conjugates as a cation/anion symporter, which can transport both Na+ and Cl− across lipid bilayers with relatively high transport activity. Surprisingly, the ion transport activities were diminished when high concentrations of K+ ions were present outside the vesicles. This unusual behavior resulted from the strong affinity of the transporters for K+ ions, which led to predominant partitioning of the transporters as the K+ complexes in the aqueous phase preventing the transporter incorporation into the membrane. Synthetic membrane transporters with Na+, Cl− and K+ transport capabilities may have potential biological and medicinal applications. [Figure not available: see fulltext.]
- Published
- 2021
33. The furosemide stress test and computational modeling identify renal damage sites associated with predisposition to acute kidney injury in rats
- Author
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Ana I. Morales, Paula Toral, Francisco J. López-Hernández, Anita T. Layton, Carlos Martínez-Salgado, Isabel Fuentes-Calvo, María T. Hernández-Sánchez, Alfredo G. Casanova, María T. Caballero, Nélida Eleno, and Miguel Quintero
- Subjects
Male ,0301 basic medicine ,medicine.medical_specialty ,Diuresis ,Renal function ,Antineoplastic Agents ,Kidney ,urologic and male genital diseases ,Excretion ,03 medical and health sciences ,0302 clinical medicine ,Furosemide ,Physiology (medical) ,Internal medicine ,medicine ,Animals ,Computer Simulation ,Subclinical infection ,business.industry ,Biochemistry (medical) ,Public Health, Environmental and Occupational Health ,Acute kidney injury ,General Medicine ,Acute Kidney Injury ,medicine.disease ,Anti-Bacterial Agents ,Rats ,030104 developmental biology ,Endocrinology ,030220 oncology & carcinogenesis ,Symporter ,Biomarker (medicine) ,Cisplatin ,Gentamicins ,business ,medicine.drug - Abstract
Acute kidney injury (AKI) diagnosis relies on plasma creatinine concentration (Crpl), a relatively insensitive, surrogate biomarker of glomerular filtration rate that increases only after significant damage befalls. However, damage in different renal structures may occur without increments in Crpl, a condition known as subclinical AKI. Thus, detection of alterations in other aspects of renal function different from glomerular filtration rate must be included in an integral diagnosis of AKI. With this aim, we adapted to and validated in rats (for preclinical research) the furosemide stress test (FST), a tubular function test hitherto performed only in humans. We also tested its sensitivity in detecting subclinical tubular alterations. In particular, we predisposed rats to AKI with 3 mg/kg cisplatin and subsequently subjected them to a triggering insult (ie, 50 mg/kg/d gentamicin for 6 days) that had no effect on nonpredisposed animals but caused an overt AKI in predisposed rats. The FST was performed immediately before adding the triggering insult. Predisposed animals showed a reduced response to the FST (namely, reduced furosemide-induced diuresis and K+ excretion), whereas nonpredisposed animals showed no alteration, compared to the controls. Computational modeling of epithelial transport of solutes and water along the nephrons applied to experimental data suggested that proximal tubule transport was only minimally reduced, the sodium-chloride symporter was upregulated by 50%, and the renal outer medullary potassium channel was downregulated by 85% in predisposed animals. In conclusion, serial coupling of the FST and computational modeling may be used to detect and localize subclinical tubular alterations.
- Published
- 2021
34. The two-domain elevator-type mechanism of zinc-transporting ZIP proteins
- Author
-
Wiuf, Anders, Steffen, Jonas Hyld, Becares, Eva Ramos, Gronberg, Christina, Mahato, Dhani Ram, Rasmussen, Soren G. F., Andersson, Magnus, Croll, Tristan, Gotfryd, Kamil, Gourdon, Pontus, Wiuf, Anders, Steffen, Jonas Hyld, Becares, Eva Ramos, Gronberg, Christina, Mahato, Dhani Ram, Rasmussen, Soren G. F., Andersson, Magnus, Croll, Tristan, Gotfryd, Kamil, and Gourdon, Pontus
- Abstract
Zinc is essential for all organisms and yet detrimental at elevated levels. Hence, homeostasis of this metal is tightly regulated. The Zrt/Irt-like proteins (ZIPs) represent the only zinc importers in metazoans. Mutations in human ZIPs cause serious disorders, but the mechanism by which ZIPs transfer zinc remains elusive. Hitherto, structural information is only available for a model member, BbZIP, and as a single, ion-bound conformation, precluding mechanistic insights. Here, we elucidate an inward-open metal-free BbZIP structure, differing substantially in the relative positions of the two separate domains of ZIPs. With accompanying coevolutional analyses, mutagenesis, and uptake assays, the data point to an elevator-type transport mechanism, likely shared within the ZIP family, unifying earlier functional data. Moreover, the structure reveals a previously unknown ninth transmembrane segment that is important for activity in vivo. Our findings outline the mechanistic principles governing ZIP-protein transport and enhance the molecular understanding of ZIP-related disorders.
- Published
- 2022
35. Forty Four Years With Baruch Kanner and The Chloride Ion
- Author
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Gary Rudnick
- Subjects
0301 basic medicine ,Neurotransmitter transporter ,Neurotransmitter Agents ,Symporters ,Sodium ,education ,Membrane Transport Proteins ,General Medicine ,History, 20th Century ,History, 21st Century ,Biochemistry ,Article ,humanities ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,030104 developmental biology ,0302 clinical medicine ,Chlorides ,Symporter ,Amino Acids ,Psychology ,030217 neurology & neurosurgery - Abstract
Baruch Kanner and this author have had parallel careers investigating neurotransmitter transporters. At multiple times during their careers, they have found themselves collaborating or competing, but always learning from each other. This commentary elaborates on the interactions between the Kanner and Rudnick laboratories, with a focus on transporters in the Neurotransmitter: Sodium Symporter (NSS) family of amino acid and amine transporters. A key focus of these interactions is the mechanism by which chloride ions activate and drive transport.
- Published
- 2021
36. A Novel SLC5A5 Variant Reveals the Crucial Role of Kinesin Light Chain 2 in Thyroid Hormonogenesis
- Author
-
Carlos P. Modenutti, Ana María Masini-Repiso, Victoria Peyret, Gabriela Coux, Liliana Muñoz, Juan Pablo Nicola, Mariano Martín, Mirta Miras, Mauco Lucas Gil Rosas, Nora B. Calcaterra, Nancy Carrasco, Romina Celeste Geysels, Graciela Testa, Gabriela Sobrero, Carlos Eduardo Bernal Barquero, Marcelo A. Martí, and Malvina Signorino
- Subjects
Male ,Sodium-iodide symporter ,Thyroid Hormones ,medicine.medical_specialty ,Endocrinology, Diabetes and Metabolism ,Clinical Biochemistry ,Mutation, Missense ,Thyroid Gland ,Kinesins ,Context (language use) ,Biochemistry ,Endocrinology ,Internal medicine ,Congenital Hypothyroidism ,medicine ,Animals ,Humans ,Missense mutation ,health care economics and organizations ,Clinical Research Articles ,Gene knockdown ,Symporters ,Chemistry ,Biochemistry (medical) ,Thyroid ,Infant, Newborn ,Iodides ,medicine.disease ,Molecular biology ,Rats ,Congenital hypothyroidism ,Gene expression profiling ,Phenotype ,medicine.anatomical_structure ,Symporter ,Microtubule-Associated Proteins ,Metabolism, Inborn Errors - Abstract
Context Iodide transport defect (ITD) (Online Mendelian Inheritance in Man No. 274400) is an uncommon cause of dyshormonogenic congenital hypothyroidism due to loss-of-function variants in the SLC5A5 gene, which encodes the sodium/iodide symporter (NIS), causing deficient iodide accumulation in thyroid follicular cells. Objective This work aims to determine the molecular basis of a patient’s ITD clinical phenotype. Methods The propositus was diagnosed with dyshormonogenic congenital hypothyroidism with minimal 99mTc-pertechnetate accumulation in a eutopic thyroid gland. The propositus SLC5A5 gene was sequenced. Functional in vitro characterization of the novel NIS variant was performed. Results Sanger sequencing revealed a novel homozygous missense p.G561E NIS variant. Mechanistically, the G561E substitution reduces iodide uptake, because targeting of G561E NIS to the plasma membrane is reduced. Biochemical analyses revealed that G561E impairs the recognition of an adjacent tryptophan-acidic motif by the kinesin-1 subunit kinesin light chain 2 (KLC2), interfering with NIS maturation beyond the endoplasmic reticulum, and reducing iodide accumulation. Structural bioinformatic analysis suggests that G561E shifts the equilibrium of the unstructured tryptophan-acidic motif toward a more structured conformation unrecognizable to KLC2. Consistently, knockdown of Klc2 causes defective NIS maturation and consequently decreases iodide accumulation in rat thyroid cells. Morpholino knockdown of klc2 reduces thyroid hormone synthesis in zebrafish larvae leading to a hypothyroid state as revealed by expression profiling of key genes related to the hypothalamic-pituitary-thyroid axis. Conclusion We report a novel NIS pathogenic variant associated with dyshormonogenic congenital hypothyroidism. Detailed molecular characterization of G561E NIS uncovered the significance of KLC2 in thyroid physiology.
- Published
- 2021
37. De novo mutation in SLC25A22 gene: expansion of the clinical and electroencephalographic phenotype
- Author
-
Vincenzo Salpietro, Stephanie Efthymiou, Patrizia Mondello, Antonio Gennaro Nicotera, Anna Cafeo, Gabriella Di Rosa, Henry Houlden, Daniela Dicanio, Erica Pironti, and Maria Bonsignore
- Subjects
0301 basic medicine ,Genetics ,Oculogyric crisis ,Dyskinetic movements ,SLC25A22 gene ,epileptic encephalopathy ,glutamate ,oculogyric crisis ,Biology ,medicine.disease ,Hypotonia ,3. Good health ,Solute carrier family ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,030104 developmental biology ,0302 clinical medicine ,Symporter ,medicine ,Missense mutation ,medicine.symptom ,Inner mitochondrial membrane ,030217 neurology & neurosurgery ,Mitochondrial transport ,Exome sequencing - Abstract
The SLC25A22 (Solute Carrier Family 25, Member 22) gene encodes for a mitochondrial glutamate/H+ symporter and is involved in the mitochondrial transport of metabolites across the mitochondrial membrane. We hereby report a 12-year-old girl presenting with early-onset epileptic encephalopathy, hypotonia, and global developmental delay. Whole exome sequencing identified a novel homozygous missense mutation in SLC25A22 gene (c.97A>G; p.Lys33Glu), as the likely cause of the disease. The phenotype of our patient and EEG recordings do not completely overlap with the phenotypes previously described, leading to a new and more complex form of disease associated with SLC25A22 variants, characterized by dyskinetic movements and oculogyric crisis.
- Published
- 2021
38. The genome of the gymnosperm Picea glauca encodes a single Nucleobase Cation Symporter 1 (PgNCS1) that displays a broad yet unique solute specificity profile
- Author
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George Mourad, Candace R. Alexander, Kevin A. Hunt, Jessica R. Schein, Mahanish J. Thapa, Laura Mack, and Neil P. Schultes
- Subjects
0106 biological sciences ,Guanine ,Nucleobase transport ,Uracil ,Horticulture ,Biology ,Xanthine ,01 natural sciences ,Nucleobase ,chemistry.chemical_compound ,chemistry ,Biochemistry ,Symporter ,Hypoxanthine ,Cytosine ,010606 plant biology & botany - Abstract
The Picea glauca genome contains a locus that encodes for a nucleobase cation symporter 1 (PgNCS1). As a gymnosperm, P. glauca belongs to a key taxonomic position for an ongoing evolution-function analysis of viridiplantae nucleobase cation symporter 1 proteins (NCS1). Here the solute transport and binding properties for PgNCS1 are determined through heterologous expression in Saccharomyces cerevisiae strains deficient in functional NCS1 loci. PgNCS1 displays a broad, yet unique, solute specificity profile –common with other plant NCS1. Yeast containing PgNCS1 transport adenine, guanine, hypoxanthine, xanthine and uracil and are sensitive to growth on 8-azaadenine. Neither cytosine nor 5 flourocytosine are transported by PgNCS1 but along with caffeine and uric acid, act as competitive inhibitors of [3H]-adenine and [3H]-hypoxanthine uptake. This transporter displays high affinity for adenine (Km = 2.67 μM), guanine (Ki = 1.71 μM) and hypoxanthine (Ki = 1.82 μM) but lesser affinity for xanthine (Ki = 5.36 μM). Arabidopsis plants that are deficient in their endogenous NCS1, yet carry PgNCS1, show significant uptake of [3H]-adenine. The results support previous studies and together confirm a broad nucleobase transport and binding pattern for plant NCS1 across the viridiplantae. PgNCS1 displays a broad yet unique nucleosbase transport and binding profile. It transports adenine, guanine, hypoxanthine, xanthine and uracil but only binds cytosine, caffeine, and uric acid.
- Published
- 2021
39. Biochemical and biophysical pH clamp controlling Net H + efflux across the plasma membrane of plant cells
- Author
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Min Yu, Sergey Shabala, Jie Zhang, Li Xuewen, Lars H. Wegner, and Zhifeng Hao
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0106 biological sciences ,0301 basic medicine ,biology ,Physiology ,Chemistry ,Chemiosmosis ,ATPase ,Bicarbonate ,Plant Science ,01 natural sciences ,Antiporters ,Apoplast ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,Symporter ,biology.protein ,Biophysics ,Efflux ,Phosphoenolpyruvate carboxylase ,010606 plant biology & botany - Abstract
P-type H+ ATPases mediate active H+ efflux from plant cells. They generate a proton motive force across the plasma membrane, providing the free energy to drive the transport of other solutes, partly by coupling to H+ influx. Wegner & Shabala (2020) recently suggested that passive H+ influx can exceed pump-driven efflux due to 'active buffering', that is, cytosolic H+ scavenging and apoplastic H+ generation by metabolism ('biochemical pH clamp'). Charge balance is provided by K+ efflux or anion influx. Here, this hypothesis is extended to net H+ efflux: even though H+ pumping is faster than backflow via symporters and antiporters, a progressive increase in the transmembrane pH gradient is avoided. Cytosolic H+ release is associated with bicarbonate formation from CO2 . Bicarbonate serves as substrate for the PEPCase, catalyzing the reaction from phosphoenolpyruvate to oxaloacetate, which is subsequently reduced to malate. Organic anions such as malate and citrate are released across the plasma membrane and are (partly) protonated in the apoplast, thus limiting pump-induced acidification. Moreover, a 'biophysical pH clamp' is introduced, that is, adjustment of apoplastic/cytosolic pH involving net H+ fluxes across the plasma membrane, while the gradient between compartments is maintained. The clamps are not mutually exclusive but are likely to coexist.
- Published
- 2021
40. The Medicago truncatula Sugar Transport Protein 13 and Its Lr67res-Like Variant Confer Powdery Mildew Resistance in Legumes via Defense Modulation
- Author
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Deepti Jain, Divya Chandran, Shubham Dubey, and Megha Gupta
- Subjects
Sucrose ,Physiology ,Plant Science ,Biology ,Ascomycota ,Gene Expression Regulation, Plant ,Arabidopsis ,Haustorium ,Medicago truncatula ,Sugar ,Gene ,Phylogeny ,Disease Resistance ,Hexoses ,Plant Diseases ,Plant Proteins ,Chitosan ,Symporters ,Arabidopsis Proteins ,Cell Membrane ,food and beverages ,Fabaceae ,Cell Biology ,General Medicine ,Plants, Genetically Modified ,biology.organism_classification ,Glucose ,Biochemistry ,Host-Pathogen Interactions ,Mutation ,Symporter ,Erysiphe pisi ,Powdery mildew - Abstract
Obligate biotrophic pathogens like the pea powdery mildew© (PM) Erysiphe pisi establish long-term feeding relationships with their host, during which they siphon sugars from host cells through haustoria. Plants in turn deploy sugar transporters to restrict carbon allocation toward pathogens, as a defense mechanism. Studies in Arabidopsis have shown that sugar transport protein 13 (STP13), a proton-hexose symporter involved in apoplasmic hexose retrieval, contributes to bacterial and necrotrophic fungal resistance by limiting sugar flux toward these pathogens. By contrast, expression of Lr67res,a transport-deficient wheat STP13 variant harboring two amino acid substitutions (G144R and V387L), conferred resistance against biotrophic fungi in wheat and barley, indicating its broad applicability in disease management. Here, we investigated the role of STP13 and STP13G144R in legume–PM interactions. We show that Medicago truncatula STP13.1 is a proton-hexose symporter involved in basal resistance against PM and indirectly show that Lr67res-mediated PM resistance, so far reported only in monocots, is transferable to legumes. Among the 30 MtSTPs, STP13.1 exhibited the highest fold induction in PM-challenged leaves and was also responsive to chitosan, ABA and sugar treatment. Functional assays in yeast showed that introduction of the G144R mutation but not V388L abolished MtSTP13.1’s hexose uptake ability. Virus-induced gene silencing of MtSTP13 repressed pathogenesis-related (PR) gene expression and enhanced PM susceptibility in M. truncatula whereas transient overexpression of MtSTP13.1 or MtSTP13.1G144R in pea induced PR and isoflavonoid pathway genes and enhanced PM resistance. We propose a model in which STP13.1-mediated sugar signaling triggers defense responses against PM in legumes.
- Published
- 2021
41. Evaluating the Natrium Iodide Symporter Expressions in Thyroid Tumors
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Rony Rustam, Aisyah Elliyanti, Yayi Dwina Billianti Susanto, Yenita Yenita, and Tofrizal Tofrizal
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endocrine system diseases ,Adenoma ,Papillary thyroid cancer ,chemistry.chemical_element ,Western blot ,030209 endocrinology & metabolism ,Iodine ,Follicular thyroid cancer ,03 medical and health sciences ,0302 clinical medicine ,medicine ,030212 general & internal medicine ,Thyroid cancer ,health care economics and organizations ,business.industry ,Thyroid ,General Medicine ,medicine.disease ,Immunohistochemistry ,Molecular biology ,medicine.anatomical_structure ,chemistry ,Membrane staining ,Symporter ,business - Abstract
BACKGROUND: Decreased Natrium iodide symporter (NIS) expression levels or diminished NIS targeting thyroid cancer cells’ plasma membrane leads to radioiodine-refractory disease. AIM: The aim of this study was to analyze the NIS expression in thyroid tumors. MATERIALS AND METHODS: The samples were thyroid tissues of patients who underwent surgery for a thyroid tumor. The tissues were processed for NIS protein expressions by immunohistochemistry (IHC) and Western blot (WB). Graves’ disease samples were used as positive controls. The samples were incubated without the primary antibody, and they were used as negative controls for IHC examination. Na+/K+ ATPase was a plasma membrane protein marker in the WB procedure. RESULTS: Twenty-nine samples were assessed for NIS protein. All of them showed the expression in the cytoplasm with intensity 1+ to 3+ with Allred score 3-8. Fourteen out of 29 cases (48.2%) showed NIS cytoplasm staining intensity ≥2+ consist of 10 papillary thyroid cancer (PTC), three follicular thyroid cancer, and one adenoma. Membrane staining was found in 2 samples of PTC (6.9%). Six samples (adenoma 1 sample, PTC 5 samples) showed NIS expression at membrane very weak (1+); they were considered as negative. NIS protein has several bands of ~ 80 kDa, ~ 62 kDa, and ~ 49 kDa. CONCLUSION: NIS expression in thyroid cancer mostly expresses in the cytoplasm instead of the membrane. NIS will play a functional role in the membrane to bring iodine across the membrane against the concentration. It can be the main reason for the lack of response of radioiodine in some differentiated thyroid cancers.
- Published
- 2021
42. Regulation of solute carrier family 26 member 7 (Slc26a7) by thyroid stimulating hormone in thyrocytes
- Author
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Mitsuo Kiriya, Yuqian Luo, Akira Kawashima, Yuta Tanimura, Hitomi Mori, Tetsuo Kondo, and Koichi Suzuki
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endocrine system ,medicine.medical_specialty ,endocrine system diseases ,Endocrinology, Diabetes and Metabolism ,Thyrotropin ,Antiporters ,Cell Line ,chemistry.chemical_compound ,Endocrinology ,Thyroid-stimulating hormone ,Internal medicine ,medicine ,Animals ,Chloride-Bicarbonate Antiporters ,Forskolin ,biology ,Chemistry ,Colforsin ,Thyroid ,Pendrin ,Apical membrane ,Rats ,Solute carrier family ,medicine.anatomical_structure ,Gene Expression Regulation ,Sulfate Transporters ,Thyroid Epithelial Cells ,Symporter ,biology.protein ,Thyroid function ,hormones, hormone substitutes, and hormone antagonists - Abstract
Iodine transportation is an important step in thyroid hormone biosynthesis. Uptake of iodine into the thyroid follicle is mediated mainly by the basolateral sodium-iodide symporter (NIS or solute carrier family 5 member 5: SLC5A5), and iodine efflux across the apical membrane into the follicular lumen is mediated by pendrin (SLC26A4). In addition to these transporters, SLC26A7, which has recently been identified as a causative gene for congenital hypothyroidism, was found to encode a novel apical iodine transporter in the thyroid. Although SLC5A5 and SLC26A4 have been well-characterized, little is known about SLC26A7, including its regulation by TSH, the central hormone regulator of thyroid function. Using rat thyroid FRTL-5 cells, we showed that the mRNA levels of Slc26a7 and Slc26a4, two apical iodine transporters responsible for iodine efflux, were suppressed by TSH, whereas the mRNA level of Slc5a5 was induced. Forskolin and dibutyryl cAMP (dbcAMP) had the same effect as that of TSH on the mRNA levels of these transporters. TSH, forskolin and dbcAMP also had suppressive effects on SLC26A7 promoter activity, as assessed by luciferase reporter gene assays, and protein levels, as determined by Western blot analysis. TSH, forskolin and dbcAMP also induced strong localization of Slc26a7 to the cell membrane according to immunofluorescence staining and confocal laser scanning microscopy. Together, these results suggest that TSH suppresses the expression level of Slc26a7 but induces its accumulation at the cell membrane, where it functions as an iodine transporter.
- Published
- 2021
43. Solvent accessibility changes in a Na+-dependent C4-dicarboxylate transporter suggest differential substrate effects in a multistep mechanism
- Author
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Christopher Mulligan, Joseph A. Mindell, Connor D.D. Sampson, and Matthew J Stewart
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0301 basic medicine ,anion transport ,Conformational change ,Protein Conformation ,membrane transport ,Molecular Dynamics Simulation ,Biochemistry ,Divalent ,03 medical and health sciences ,conformational change ,Protein structure ,Protein Domains ,Membrane Biology ,Vibrio cholerae ,Molecular Biology ,Dicarboxylic Acid Transporters ,chemistry.chemical_classification ,Binding Sites ,030102 biochemistry & molecular biology ,Chemistry ,Sodium ,Substrate (chemistry) ,Biological Transport ,Transporter ,transmembrane domain ,Cell Biology ,Membrane transport ,tricarboxylic acid cycle (TCA cycle) (Krebs cycle) ,Transmembrane domain ,030104 developmental biology ,transporter ,Symporter ,tricarboxylic acid cycle ,Solvents ,Biophysics ,protein chemical modification ,QP517 ,Protein Binding - Abstract
The divalent anion sodium symporter (DASS) family (SLC13) plays critical roles in metabolic homeostasis, influencing many processes, including fatty acid synthesis, insulin resistance, and adiposity. DASS transporters catalyze the Na+-driven concentrative uptake of Krebs cycle intermediates and sulfate into cells; disrupting their function can protect against age-related metabolic diseases and can extend lifespan. An inward-facing crystal structure and an outward-facing model of a bacterial DASS family member, VcINDY from Vibrio cholerae, predict an elevator-like transport mechanism involving a large rigid body movement of the substrate-binding site. How substrate binding influences the conformational state of VcINDY is currently unknown. Here, we probe the interaction between substrate binding and protein conformation by monitoring substrate-induced solvent accessibility changes of broadly distributed positions in VcINDY using a site-specific alkylation strategy. Our findings reveal that accessibility to all positions tested is modulated by the presence of substrates, with the majority becoming less accessible in the presence of saturating concentrations of both Na+ and succinate. We also observe separable effects of Na+ and succinate binding at several positions suggesting distinct effects of the two substrates. Furthermore, accessibility changes to a solely succinate-sensitive position suggests that substrate binding is a low-affinity, ordered process. Mapping these accessibility changes onto the structures of VcINDY suggests that Na+ binding drives the transporter into an as-yet-unidentified conformational state, involving rearrangement of the substrate-binding site–associated re-entrant hairpin loops. These findings provide insight into the mechanism of VcINDY, which is currently the only structurally characterized representative of the entire DASS family.
- Published
- 2020
44. Revision of the affinity constant for perchlorate binding to the sodium-iodide symporter based on in vitro and human in vivo data.
- Author
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Schlosser, Paul M.
- Subjects
SODIUM cotransport systems ,PHARMACOKINETICS ,PERCHLORATES ,SODIUM iodide ,MICHAELIS-Menten mechanism - Abstract
A series of previously published physiologically based pharmacokinetic (PBPK) models describe the effect of perchlorate on iodide uptake by the thyroid, with the mechanism being competitive inhibition of iodide transport by the sodium-iodide symporter (NIS). Hence a key parameter of these models is the affinity of perchlorate for the NIS, characterized as the Michaelis-Menten kinetic constant, K
m . However, when model predictions were compared to published results of a human study measuring radio-iodide uptake (RAIU) inhibition after controlled perchlorate exposures, it was found to only fit the lowest exposure level and underpredicted RAIU inhibition at higher levels. Published in vitro data, in which perchlorate-induced inhibition of iodide uptake via the NIS was measured, were re-analyzed. Km for binding of perchlorate to the NIS originally derived from these data, 1.5 μ m, had been obtained using Lineweaver-Burk plots, which allow for linear regression but invert the signal-noise of the data. Re-fitting these data by non-linear regression of the non-inverted data yielded a 60% lower value for the Km , 0.59 μ m. Substituting this value into the PBPK model for an average adult human significantly improved model agreement with the human RAIU data for exposures <100 μg kg−1 day−1 . Thus, this lower Km value both fits the in vitro NIS kinetics and provides better predictions of human in vivo RAIU data. This change in Km increases the predicted sensitivity of humans to perchlorate over twofold for low-level exposures. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
45. The K+ and NO3− Interaction Mediated by NITRATE TRANSPORTER1.1 Ensures Better Plant Growth under K+-Limiting Conditions
- Author
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Xian Zhi Fang, Ya Xing Zhu, Chong Wei Jin, Xing Xing Liu, and Jia Yuan Ye
- Subjects
0106 biological sciences ,Genotype ,Physiology ,Potassium ,Anion Transport Proteins ,Mutant ,Arabidopsis ,chemistry.chemical_element ,Plant Science ,Genes, Plant ,Plant Roots ,01 natural sciences ,Gene Expression Regulation, Plant ,Genetics ,Arabidopsis thaliana ,Potassium Deficiency ,Research Articles ,Nitrates ,biology ,Arabidopsis Proteins ,Chemistry ,Genetic Variation ,Biological Transport ,Transporter ,Promoter ,biology.organism_classification ,Nitrogen ,Mutation ,Symporter ,Biophysics ,Plant Shoots ,010606 plant biology & botany - Abstract
K(+) and NO(3)(−) are the major forms of potassium and nitrogen that are absorbed by the roots of most terrestrial plants. In this study, we observed that a close relationship between NO(3)(−) and K(+) in Arabidopsis (Arabidopsis thaliana) is mediated by NITRATE TRANSPORTER1.1 (NRT1.1). The nrt1.1 knockout mutants showed disturbed K(+) uptake and root-to-shoot allocation, and were characterized by growth arrest under K(+)-limiting conditions. The K(+) uptake and root-to-shoot allocation of these mutants were partially recovered by expressing NRT1.1 in the root epidermis-cortex and central vasculature using SULFATE TRANSPORTER1;2 and PHOSPHATE1 promoters, respectively. Two-way analysis of variance based on the K(+) contents in nrt1.1-1/K(+) transporter1, nrt1.1-1/high-affinity K(+) transporter5-3, nrt1.1-1/K(+) uptake permease7, and nrt1.1-1/stelar K(+) outward rectifier-2 double mutants and the corresponding single mutants and wild-type plants revealed physiological interactions between NRT1.1 and K(+) channels/transporters located in the root epidermis–cortex and central vasculature. Further study revealed that these K(+) uptake-related interactions are dependent on an H(+)-consuming mechanism associated with the H(+)/NO(3)(−) symport mediated by NRT1.1. Collectively, these data indicate that patterns of NRT1.1 expression in the root epidermis–cortex and central vasculature are coordinated with K(+) channels/transporters to improve K(+) uptake and root-to-shoot allocation, respectively, which in turn ensures better growth under K(+)-limiting conditions.
- Published
- 2020
46. Gut Microbiome and Radioiodine-Refractory Papillary Thyroid Carcinoma Pathophysiology
- Author
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Vahid Haghpanah and Hilda Samimi
- Subjects
Sodium-iodide symporter ,endocrine system diseases ,Endocrinology, Diabetes and Metabolism ,030209 endocrinology & metabolism ,Iodine Radioisotopes ,Thyroid carcinoma ,03 medical and health sciences ,0302 clinical medicine ,Endocrinology ,Refractory ,hemic and lymphatic diseases ,Humans ,Medicine ,Prion protein ,Symporters ,business.industry ,medicine.disease ,Carcinoma, Papillary ,Pathophysiology ,Gut microbiome ,Gastrointestinal Microbiome ,Thyroid Cancer, Papillary ,Symporter ,Cancer research ,business ,Dysbiosis - Abstract
Gut microbiome (GM) might be associated with radioiodine (RAI)-refractory papillary thyroid carcinoma (PTC) through different mechanisms related to sodium/iodide (Na+/I–) symporter (NIS) regulation. However, whether thyroid carcinoma (TC), especially RAI-refractory PTC, causes dysbiosis, or vice versa, is still unknown. Further studies are needed to investigate the mechanism between GM and RAI-refractory PTC.
- Published
- 2020
47. The paradoxical lean phenotype of hypothyroid mice is marked by increased adaptive thermogenesis in the skeletal muscle
- Author
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Andrea Reyna-Neyra, Sandro M. Hirabara, Lara Jung, Nancy Carrasco, Alejandra Paola Torres-Manzo, and Rachel R. Kaspari
- Subjects
Male ,0301 basic medicine ,endocrine system ,medicine.medical_specialty ,endocrine system diseases ,Proteolipids ,Muscle Proteins ,030209 endocrinology & metabolism ,Eating ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Hypothyroidism ,Internal medicine ,medicine ,Animals ,Euthyroid ,Muscle, Skeletal ,Beta oxidation ,Mice, Knockout ,Multidisciplinary ,Symporters ,business.industry ,Thyroid ,Skeletal muscle ,Thermogenesis ,Biological Sciences ,Sarcolipin ,Disease Models, Animal ,Phenotype ,030104 developmental biology ,medicine.anatomical_structure ,Endocrinology ,Symporter ,medicine.symptom ,business ,Weight gain ,Hormone - Abstract
Obesity is a major health problem worldwide, given its growing incidence and its association with a variety of comorbidities. Weight gain results from an increase in energy intake without a concomitant increase in energy expenditure. To combat the obesity epidemic, many studies have focused on the pathways underlying satiety and hunger signaling, while other studies have concentrated on the mechanisms involved in energy expenditure, most notably adaptive thermogenesis. Hypothyroidism in humans is typically associated with a decreased basal metabolic rate, lower energy expenditure, and weight gain. However, hypothyroid mouse models have been reported to have a leaner phenotype than euthyroid controls. To elucidate the mechanism underlying this phenomenon, we used a drug-free mouse model of hypothyroidism: mice lacking the sodium/iodide symporter (NIS), the plasma membrane protein that mediates active iodide uptake in the thyroid. In addition to being leaner than euthyroid mice, owing in part to reduced food intake, these hypothyroid mice show signs of compensatory up-regulation of the skeletal-muscle adaptive thermogenic marker sarcolipin, with an associated increase in fatty acid oxidation (FAO). Neither catecholamines nor thyroid-stimulating hormone (TSH) are responsible for sarcolipin expression or FAO stimulation; rather, thyroid hormones are likely to negatively regulate both processes in skeletal muscle. Our findings indicate that hypothyroidism in mice results in a variety of metabolic changes, which collectively lead to a leaner phenotype. A deeper understanding of these changes may make it possible to develop new strategies against obesity.
- Published
- 2020
48. Sodium-coupled glucose transport, the SLC5 family, and therapeutically relevant inhibitors: from molecular discovery to clinical application
- Author
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Yoshikatsu Kanai, Gergely Gyimesi, Matthias A. Hediger, and Jonai Pujol-Giménez
- Subjects
SLC5 family ,0301 basic medicine ,Glucose transport ,Physiology ,Clinical Biochemistry ,Tubuloglomerular feedback ,610 Medicine & health ,Computational biology ,SGLT2 ,Sodium-Glucose Transport Proteins ,SGLT1 ,Nephroprotective ,03 medical and health sciences ,Gliflozins ,0302 clinical medicine ,Physiology (medical) ,Drug Discovery ,Diabetes Mellitus ,Animals ,Humans ,Sodium-Glucose Transporter 2 Inhibitors ,Cancer ,Invited Review ,biology ,Drug discovery ,Diabetes ,Glucose transporter ,Renal Reabsorption ,Molecular medicine ,3. Good health ,Solute carrier family ,030104 developmental biology ,Intestinal Absorption ,Drug development ,Molecular docking ,Drug delivery ,Symporter ,biology.protein ,570 Life sciences ,Renin-angiotensin system ,Cotransporter ,SGLT2 inhibitors ,030217 neurology & neurosurgery ,Sodium-glucose transport proteins - Abstract
Sodium glucose transporters (SGLTs) belong to the mammalian solute carrier family SLC5. This family includes 12 different members in human that mediate the transport of sugars, vitamins, amino acids, or smaller organic ions such as choline. The SLC5 family belongs to the sodium symporter family (SSS), which encompasses transporters from all kingdoms of life. It furthermore shares similarity to the structural fold of the APC (amino acid-polyamine-organocation) transporter family. Three decades after the first molecular identification of the intestinal Na+-glucose cotransporter SGLT1 by expression cloning, many new discoveries have evolved, from mechanistic analysis to molecular genetics, structural biology, drug discovery, and clinical applications. All of these advances have greatly influenced physiology and medicine. While SGLT1 is essential for fast absorption of glucose and galactose in the intestine, the expression of SGLT2 is largely confined to the early part of the kidney proximal tubules, where it reabsorbs the bulk part of filtered glucose. SGLT2 has been successfully exploited by the pharmaceutical industry to develop effective new drugs for the treatment of diabetic patients. These SGLT2 inhibitors, termed gliflozins, also exhibit favorable nephroprotective effects and likely also cardioprotective effects. In addition, given the recent finding that SGLT2 is also expressed in tumors of pancreas and prostate and in glioblastoma, this opens the door to potential new therapeutic strategies for cancer treatment by specifically targeting SGLT2. Likewise, further discoveries related to the functional association of other SGLTs of the SLC5 family to human pathologies will open the door to potential new therapeutic strategies. We furthermore hope that the herein summarized information about the physiological roles of SGLTs and the therapeutic benefits of the gliflozins will be useful for our readers to better understand the molecular basis of the beneficial effects of these inhibitors, also in the context of the tubuloglomerular feedback (TGF), and the renin-angiotensin system (RAS). The detailed mechanisms underlying the clinical benefits of SGLT2 inhibition by gliflozins still warrant further investigation that may serve as a basis for future drug development.
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- 2020
49. The benefit of elobixibat in chronic constipation is associated with faecal deoxycholic acid but not effects of altered microbiota
- Author
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Koichiro Wada, Haruki Usuda, Michael Camilleri, Hajime Takei, Keiichi Ashikari, Atsushi Nakajima, Akiko Fuyuki, Takaomi Kessoku, Noboru Misawa, Tomohiro Takatsu, Hiroshi Nittono, Nakayuki Naritaka, Tetsuya Matsuura, Michihiro Iwaki, Takashi Kobayashi, Mitsuharu Matsumoto, Hidenori Ohkubo, Takuma Higurashi, Akira Honda, and Tsutomu Yoshihara
- Subjects
Adult ,Male ,medicine.medical_specialty ,Organic anion transporter 1 ,Colon ,Thiazepines ,medicine.drug_class ,Organic Anion Transporters, Sodium-Dependent ,Gut flora ,digestive system ,Gastroenterology ,Bile Acids and Salts ,Feces ,03 medical and health sciences ,chemistry.chemical_compound ,fluids and secretions ,0302 clinical medicine ,Elobixibat ,Internal medicine ,medicine ,Humans ,Pharmacology (medical) ,Prospective Studies ,030212 general & internal medicine ,Defecation ,Aged ,Chronic constipation ,Symporters ,Hepatology ,biology ,Bile acid ,business.industry ,Microbiota ,digestive, oral, and skin physiology ,Deoxycholic acid ,Dipeptides ,Middle Aged ,biology.organism_classification ,chemistry ,Symporter ,biology.protein ,Female ,030211 gastroenterology & hepatology ,business ,Constipation ,Deoxycholic Acid - Abstract
BACKGROUND Elobixibat, a novel inhibitor of apical sodium-dependent bile acid transporter for treating chronic constipation, increases colonic bile acid concentrations, stimulating bowel function. However, it is not clear which bile acids are altered, or whether altered gut microbiota are associated with functional effects that may alter bowel function. AIMS To investigate the effects of elobixibat on changes in the faecal concentrations of total and individual bile acids and in faecal microbiota. METHODS This was a prospective, single-centre study. After baseline period, patients received 10 mg daily of elobixibat for 2 weeks. We evaluated the effects on bowel function, changes in faecal bile acid concentrations and composition of gut bacteria, before and after elobixibat administration. RESULTS In the 30 patients analysed, the frequency of pre- and post-treatment bowel movements per fortnight was 7 and 10 (P
- Published
- 2020
50. Grafting of glycine, alanine, serine, and threonine on cellulose membranes and their role in regulating the uniport, symport, and antiport permeation of glucose
- Author
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Zaher A. Algharaibeh, Mazin Y. Shatnawi, Mohammad H. Abdallah, and Isam M. Arafa
- Subjects
Alanine ,chemistry.chemical_classification ,010407 polymers ,Polymers and Plastics ,General Chemical Engineering ,01 natural sciences ,0104 chemical sciences ,Analytical Chemistry ,Amino acid ,Serine ,chemistry.chemical_compound ,surgical procedures, operative ,Membrane ,chemistry ,Biochemistry ,Glycine ,Symporter ,Cellulose ,Threonine - Abstract
Four cellulose membranes were grafted with glycine, L-alanine, L-serine, and L-threonine amino acids. The grafted membranes were characterized by different physicochemical techniques (ATR-IR, gravi...
- Published
- 2020
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