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188 results on '"Barisas, B. George"'

14. The mast cell function-associated antigen and its interactions with the type I Fcepsilon receptor

Author

Song, Jinming, Hagen, Guy M., Roess, Deborah A., Pecht, Israel, and Barisas, B. George

Subjects
Immune response -- Regulation, Mast cells -- Immunology, Cell receptors -- Physiological aspects, Glycoproteins -- Physiological aspects, Biological sciences, Chemistry
Abstract

Research examines the glycoprotein, mast cell function-associated antigen(MAFA), of its inhibition of the associated type I Fcepsilon receptor. Data indicate that unperturbed MAFA associates with clusters of the receptor and interacts with it.

Published
2002

22. Self-association of class I major histocompatibility complex molecules in liposome and cell surface membranes

Author

Chakrabarti, Abhijit, Matko, Janos, Rahman, Noorul A., Barisas, B. George, and Edidin, Michael

Subjects
Major histocompatibility complex -- Physiological aspects, Liposomes -- Research, Cell membranes -- Research, Biological sciences, Chemistry
Abstract

Aggregation of major histocompatibility complex (MHC) class I was investigated using fluorescent-labeled HLA-A2 reconstituted in liposomes. Results show that HLA-A2 aggregation is dependent on protein concentration and temperature with aggregation prevalent at low concentration. The aggregates have a radii four to five times that of a single monomer. The aggregation is not found in liposomes with glycophorin reconstituted in them. Beta2-microglobulin was also demonstrated to block HLA-A2 aggregation. Class I MHC aggregation can also be observed on the plasma membrane of B-lymphoblast.

Published
1992

28. Influence of omega-3 fatty acids on bovine luteal cell plasma membrane dynamics.1

Author

Plewes, Michele R., Burns, Patrick D., Hyslop, Richard M., and Barisas, B. George

Subjects
endocrine system, Docosahexaenoic Acids, Dose-Response Relationship, Drug, Primary Cell Culture, Receptors, Prostaglandin, Article, Membrane Lipids, Protein Transport, Membrane Microdomains, Eicosapentaenoic Acid, Luteal Cells, Animals, lipids (amino acids, peptides, and proteins), Cattle, Female
Abstract

Fish oil is a rich source of omega-3 fatty acids which disrupt lipid microdomain structure and affect mobility of the prostaglandin F2α (FP) receptor in bovine luteal cells. The objectives of this study were to determine the effects of individual omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on 1) membrane fatty acid composition, 2) lipid microdomain structure, and 3) lateral mobility of the FP receptor in bovine luteal cells. Ovaries were collected from a local abattoir (n = 5/experiment). The corpus luteum was resected and enzymatically digested using collagenase to generate a mixed luteal cell population. In all experiments, luteal cells were treated with 0, 1, 10 or 100 μM EPA or DHA for 72 h to allow incorporation of fatty acids into membrane lipids. Results from experiment 1 show that culturing luteal cells in the presence of EPA or DHA increased these luteal fatty acids. In experiment 2, both EPA and DHA increased spatial distribution of lipid microdomains in a dose-dependent manner. Single particle tracking results from experiment 3 show that increasing both EPA and DHA concentrations increased micro- and macro-diffusion coefficients, increased domain size, and decreased residence time of FP receptors. Collectively, results from this study demonstrate similar effects of EPA and DHA on lipid microdomain structure and lateral mobility of FP receptors in cultured bovine luteal cells. Moreover, only 10 μM of either fatty acid was needed to mimic the effects of fish oil.

Published
2017

31. Fluorescence Observation of Single-Cell cAMP Signaling by G Protein-Coupled Receptors.

Author

Zhang, Dongmei, Hadhoud, Giuma E., Helm, Karen, Roess, Deborah A., and Barisas, B. George

Subjects
G protein coupled receptors, FORSKOLIN, LUTEINIZING hormone receptors, CELL receptors, FLUORESCENT proteins, MEMBRANE proteins
Abstract

We present complementary flow cytometric and microscopic imaging methods, both utilizing a membrane-targeted cAMP sensor protein ICUE3, to examine hormone-dependent signaling by the luteinizing hormone (LH) receptor in individual cells. This receptor, a seven transmembrane domain protein belonging to the GPCR family, signals by activating adenylate cyclase to increase cAMP levels. The ICUE3 sensor protein exhibits fluorescence energy transfer between its CFP and YFP moieties and the ratio of CFP emission to YFP sensitized emission (YFPSE) increases with cAMP concentration. We used multichannel flow cytometry to compare CFP emission and YFPSE from each cell and hence measure that cell's cAMP level. This technique measured changes in cAMP levels in CHO cells expressing LH receptors and stimulated by forskolin or the hormone human chorionic gonadotropin (hCG) and showed that significant cell-to-cell variations exist in such cAMP responses. Because LH receptor behavior may reflect receptor expression levels, we developed a procedure to measure numbers of particular fluorescent cell proteins from measurements of MESF bead standards for slightly different fluorophores. We find that basal cAMP levels increase substantially in cells expressing high numbers mCherry-LH receptors per cell. This suggests activation through increased inter-receptor interactions at high concentrations. We then explored a microscope-based method for single cell measurements so that responses could be correlated with specific cell morphology and with time after treatments. This showed that cell responses to hCG are fully-developed after ~100 s. Taken together, these results demonstrate the utility of fluorescence methods in exploring cAMP signaling in individual cells. [ABSTRACT FROM AUTHOR]

Published
2019
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33. Förster distances for FRET between mCherry and other Visible Fluorescent Proteins

Author

Akrap, Nina, Seidel, Thorsten, and Barisas, B. George

Subjects
Luminescent Proteins, Fluorescence Resonance Energy Transfer, Article
Abstract

We present, for the red fluorescent protein mCherry acting as both fluorescence resonant energy transfer (FRET) donor and acceptor, Förster critical distance (r(0)) values with five important visible fluorescent protein (VFP) variants as well as with itself. The pair EYFP-mCherry exhibits an r(0) of 5.66nm, equaling or exceeding any combination of VFPs reported previously. Moreover, mCherry should be an excellent chromophore for homo-FRET with an r(0) of 5.10nm for energy transfer between two mCherry moieties. Finally, mCherry exhibits higher r(0) values than does DsRed. These characteristics, combined with mCherry's rapid folding and excellent spectral properties, suggest that mCherry constitutes a valuable long-wavelength hetero-FRET acceptor and probe for homo-FRET experiments.

Published
2010

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