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First, Zvonimir Dogic and his students took microtubules--threadlike proteins that make up part of the cell's internal 'cytoskeleton'--and mixed them with kinesins, motor proteins that travel along these threads like [...]

Purpose The calcium-sensitizing drug levosimendan increases myocardial contractility and, by activating K.sup.+-channels, dilates pulmonary vessels. In the acute setting, levosimendan is clinically used to treat right heart failure in pulmonary hypertension. As K.sup.+-channel activation elicits several beneficial effects in the vascular system, we hypothesized that levosimendan also attenuates the remodeling process in the monocrotaline model of rat pulmonary hypertension. Methods and results Animal subgroups received levosimendan, the K.sup.+-channel opener nicorandil, or levosimendan together with the K.sup.+-adenosine triphosphate (ATP)-sensitive potassium channel (K.sub.ATP) blocker glibenclamide. Morphometric analyses revealed that levosimendan and nicorandil attenuated the increased pulmonary vascular medial wall thickness after monocrotaline challenge. Accordingly, in vivo BrdU assays revealed that levosimendan significantly diminished proliferation of pulmonary arterial smooth muscle cells (PASMCs), and this effect was attenuated by glibenclamide. Levosimendan also reduced right ventricular hypertrophy, but this effect was not glibenclamide sensitive and not recapitulated by nicorandil. In cell culture, levosimendan had a direct inhibitory effect on the platelet-derived growth factor (PDGF)-induced proliferation of PASMCs, which however required high concentrations of the compound, pointing towards an endothelial effect. Indeed, levosimendan increased cyclic guanosine monophosphate (cGMP) in human umbilical vein endothelial cells (HUVECs) and impaired the tumor necrosis factor-[alpha] (TNF-[alpha])-induced inflammatory expression of E-selectin, intercellular adhesion molecule-1 (ICAM-1), cyclooxygenase-2 (COX-2), and monocyte chemotactic protein-1 (MCP-1). In luciferase reporter gene assays in HUVECs, levosimendan dose-dependently attenuated the TNF-[alpha]-stimulated increase of proinflammatory transcription factors activator protein 1 (AP1), hypoxia-inducible factor-1[alpha] (HIF-1[alpha]), and nuclear factor-[kappa]B (NF-[kappa]B). Conclusions Levosimendan attenuates pulmonary vascular remodeling, presumably by an antiproliferative and anti-inflammatory effect which is mediated by cellular hyperpolarization. The compound also has a direct inhibitory effect on cardiac hypertrophy, which is however K.sup.+-channel independent., Author(s): M. Revermann [sup.1] [sup.2], M. Schloss [sup.1], A. Mieth [sup.1], A. Babelova [sup.1], K. Schröder [sup.1], S. Neofitidou [sup.1], J. Buerkl [sup.1], T. Kirschning [sup.2], R. T. Schermuly [sup.3], [...]

Many cell types release ATP in response to mechanical or biochemical stimulation. The mechanisms responsible for this release, however, are not well understood and may differ among different cell types. In addition, there are numerous difficulties associated with studying the dynamics of ATP release immediately outside the cell membrane. Here, we report a new method that allows the visualization and quantification of ATP release by fluorescence microscopy. Our method utilizes a two-enzyme system that generates NADPH when ATP is present. NADPH is a fluorescent molecule that can be visualized by fluorescence microscopy using an excitation wavelength of 340 nm and an emission wavelength of 450 nm. The method is capable of detecting ATP concentrations < 1 [micro]M and has a dynamic range of up to 100 [micro]M. Using this method, we visualized and quantified ATP release from human polymorphonuclear leukocytes and Jurkat T cells. We show that upon cell stimulation, the concentrations of ATP can reach levels of up to 80 [micro]M immediately outside of the cell membrane. This new method should prove useful for the study of the mechanisms of release and functional role of ATP in various cell systems, including individual cells. purinergic signaling

Transient currents occur at rest in cortical neurones that reflect the quantal release of transmitters such as glutamate and [gamma]-aminobutyric acid (GABA). We found a bimodal amplitude distribution for spontaneously occurring inward currents recorded from mouse pyramidal neurones in situ, in acutely isolated brain slices superfused with picrotoxin. Larger events were blocked by glutamate receptor (AMPA, kainate) antagonists; smaller events were partially inhibited by P2X receptor antagonists suramin and PPADS. The decay of the larger events was selectively prolonged by cyclothiazide. Stimulation of single intracortical axons elicited quantal glutamate-mediated currents and also quantal currents with amplitudes corresponding to the smaller spontaneous inward currents. It is likely that the lower amplitude spontaneous events reflect packaged ATP release. This occurs with a lower probability than that of glutamate, and evokes unitary currents about hall the amplitude of those mediated through AMPA receptors. Furthermore, the packets of ATP appear to be released from vesicle in a subset of glutamate-containing terminals.

Experiments were performed to characterize renal hemodynamics in Thy-1 nephritic rats. A monoclonal antibody against Thy-1 was intravenously injected to induce mesangiolysis in rats, and 2 days later renal hemodynamic responses to variations in blood pressure were determined. In the first series of experiments, autoregulation of renal plasma flow (RPF) or glomerular filtration rate (GFR) was impaired in nephritic rats. In response to a reduction in blood pressure (98 [+ or -] 2 to 80 [+ or -] 1 mmHg), both RPF (4.17 [+ or -] 0.63 to 3.20 [+ or -] 0.45 ml x [min.sup.-1] x g kidney [wt.sup.-1], P < 0.05, n = 6) and GFR (0.88 [+ or -] 0.05 to 0.75 [+ or -] 0.06 ml x [min.sup.-1] x g kidney [wt.sup.-1], P < 0.05) were decreased in nephritic rats. Intravenous administration of furosemide and 30% albumin, both of which inhibit tubuloglomerular feedback, diminished renal autoregulation in control but not nephritic rats. In the second studies, the infusion of 5'-nucleotidase, an enzyme expressed on mesangial cells, into a renal artery ameliorated the magnitude of autoregulatory decrements in GFR in nephritic rats (-16 [+ or -] 5 to -6 [+ or -] 2%, P < 0.05, n = 6), but this enzyme failed to alter renal autoregulation in control rats. In the third studies, the effects of indomethacin were examined in nephritic rats. Inhibition of prostaglandin synthesis reduced RPF (4.07 [+ or -] 0.30 to 1.54 [+ or -] 0.22 ml x [min.sup.-1] x g kidney [wt.sup.-1], P < 0.05, n = 5) and GFR (1.03 [+ or -] 0.18 to 0.69 [+ or -] 0.13 ml x [min.sup.-1] x g kidney [wt.sup.-1], P < 0.05) in nephritic rats. However, cyclooxygenase inhibition failed to restore renal autoregulation in nephritic rats. Our results indicate that renal autoregulation is impaired in Thy-1 nephritis. Furthermore, the present data provide evidence that prostanoids contribute to maintain renal circulation in nephritic rats. Finally, our findings suggest that mesangial cells and/or 5'-nucleotidase plays an important role in mediating renal autoregulation. adenosine; ATP; sodium excretion; water excretion

ATP-activated currents were studied in Leydig cells of mice with the patch-clamp technique. Whole cell currents were rapidly activating and slowly desensitizing (55% decrement from the peak value on exposure to 100 [micro]M ATP for 60 s), requiring 3 min of washout to recover 100% of the response. The concentration-response relationships for ATP, adenosine 5'-O-(3-tfiiotripfiosphate) (ATP[gamma]S), and 2-methylthio-ATP (2-MeS-ATP) were described by the Hill equation with a concentration evoking 50% of maximal ATP response ([K.sub.d]) of 44, 110, and 637 [micro]M, respectively, and a Hill coefficient of 2. The order of efficacy of agonists was ATP [greater than or equal to] ATP[gamma]S > 2-MeS-ATP > 2',3'-O-(4-benzoyl-benzoyl)-ATP (BzATP). [alpha][beta]-Methylene-ATP ([alpha][beta]-MeATP), GTP, UTP, cAMP, and adenosine were ineffective. Suramin and pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS) blocked the responses in a concentration-dependent manner. The ATP-activated currents were dependent on extracellular pH, being maximal at pH 6.5 and decreasing with both acidification and alkalinization (apparent dissociation constant (p[K.sub.a]) of 5.9 and 7.4, respectively). The whole cell current-voltage relationship showed inward rectification and reversed near 0 mV. Experiments performed in bi-ionic conditions for measurement of reversal potentials showed that this channel is highly permeable to calcium [permeability [(P).sub.Ca]/[P.sub.Na] = 5.32], but not to chloride ([P.sub.C1]/[P.sub.Na] = 0.03) or N-methyl-D-glucamine (NMDG) ([P.sub.NMDG]/[P.sub.Na], = 0.09). Unitary currents recorded in outside-out patches had a chord conductance of 27 pS (between -90 and -50 mV) and were inward rectifying. The average current passing through the excised patch decreased with time [time constant ([tau]) = 13 s], resembling desensitization of the macroscopic current. These findings indicate that the ATP receptor present in Leydig cells shows properties most similar to those of cloned homomeric P2[X.sub.2] patch clamp; single channels; ATP; desensitization

The RSC and Swi/Snf ATP-dependent chromatin-remodeling complexes play key roles in double-strand break (DSB) repair, specifically by homologous recombination (HR). It is shown that Swi/Snf is required earlier, at or preceding the strand invasion step of HR, while RSC is required following synapsis for completion of the recombinational repair event.

Anaerobic starvation conditions are frequent in industrial fermentation and can affect the performance of the cells. A study is conducted to investigate the anaerobic carbon or nitrogen starvation response of Saccharomyces cerevisiae for cells grown in anaerobic carbon or nitrogen-limited chemostat cultures.

Pre-mRNA splicing requires the function of a number of RNA-dependent ATPases/helicases, yet no three-dimensional structure of any spliceosomal ATPases/helicases is known. The highly conserved DECD-box protein UAP56/Sub2 is an essential splicing factor that is also important for mRNA export. The expected ATPase/helicase activity appears to be essential for the UAP56/ Sub2 functions. Here, we show that purified human UAP56 is an active RNA-dependent ATPase, and we also report the crystal structures of UAP56 alone and in complex with ADP, as well as a DECD to DEAD mutant. The structures reveal a unique spatial arrangement of the two conserved helicase domains, and ADP-binding induces significant conformational changes of key residues in the ATP-binding pocket. Our structural analyses suggest a specific protein-RNA displacement model of UAP56/Sub2. The detailed structural information provides important mechanistic insights into the splicing function of UAP56/Sub2. The structures also will be useful for the analysis of other spliceosomal DExD-box ATPases/helicases. helicase | RNA processing | export | crystallography

The overproduction of the H4H5 loop and the nucleotide binding domain (KdpBN) of the KdpB subunit is described. It is also found that the H4H5 loop still binds and hydrolyzes ATP and p-nitrophenyl phosphate (pNPP), whereas the KdpBN domain has to only maintain the capacity to bind nucleotide.

The supramolecular interactions of 2,9-di(((2'-phenylamino) ethyleneamino)methyl)-l,10-phenanthroline (L) and (or) metal ions (M = [Ca.sup.2+], [Mg.sup.2+], [Zn.sup.2+], or [La.sup.3+]) with nucleotides were investigated. Furthermore, the hydrolysis of ATP catalyzed by a protonated ligand and (or) a metal ion (M = [Ca.sup.2+], [Mg.sup.2+], [Zn.sup.2+], or [La.sup.3+]) was studied at pH 7.6 using [sup.31]P NMR spectra. Kinetics studies show that at pH 7.6 the protonated ligand, with a rate constant of 2.9 x [10.sup.-4] [min.sup.-1], does not significantly promote ATP hydrolysis. However, in the presence of [Ca.sup.2+], [Mg.sup.2+], [Zn.sup.2+], or [La.sup.3+] ions, L can accelerate the hydrolysis of ATP, with corresponding rate constants of 5.73, 1.48, 6.76, and 31.7 x [10.sup.-3] [min.sup.-1], respectively, which are about 29-, 7.5-, 34-, and 159-fold faster than the hydrolysis rate of free ATP. By comparison with M-ATP (M = [Ca.sup.2+], [Mg.sup.2+], and [La.sup.3+]) systems, the rates of M-L-ATP were also promoted. This has been achieved through the effective recognition of ATP and the availability of a good intramolecular nucleophile, i.e., a free amino nitrogen atom of L. Compared with the [Zn.sup.2+]-ATP system, the decrease in the rate of the [Zn.sup.2+]-L-ATP system at pH 7.6 may be attributed to the competition between the mixed ligands in binding [Zn.sup.2+]. Similar to L-ATP, the hydrolysis reactions in the [Zn.sup.2+]-L-ATP or M-L-ATP (M = [Ca.sup.2+], [Mg.sup.2+], and [La.sup.3+]) systems occur through an addition--elimination type mechanism, in which phosphoramidate intermediates were observed at 2.88 and 4.06 parts per million (ppm) in the L-ATP and [Mg.sup.2+]-L-ATP systems, respectively. Here, metal ions add control or regulation to the hydrolysis reaction. Key words: recognition, ATP hydrolysis, metal ions, phenanthroline-bridged polyamine.

Activation and desensitization kinetics of the rat P2[X.sub.1] receptor at nanomolar ATP concentrations were studied in Xenopus oocytes using two-electrode voltage-clamp recording. The solution exchange system used allowed complete and reproducible solution exchange in KEY WORDS: P2X receptor desensitization * activation

Research has been conducted on the symbiotic soil bacterium Sinorhizobium meliloti. The identification of the ATP-binding cassette that binds protein-dependent transporter in S. meliloti is described.

Research has been conducted on the Pdr5p multidrug ABC ('ATP-binding cassette') transporter. The overexpression of the transporter in the yeast plasma membranes to exhibit gene disruption is discussed.

Research has been conducted on the ATP-dependent protease FtsH (HflB). Results indicate that FtsH (HflB) acts as the endopeptidase which degrades CII into small peptides with limited amino acid specificity.

The digestibility of D-tagatose, its effect on the digestibility of macronutrients and the metabolic response of the microbiota of the gastrointestinal tract to the ingestion of this carbohydrate were studied in pigs. Eight pigs were fed a low fiber diet comprising 15% sucrose (control group). Another eight pigs were fed a similar diet except that 100 g sucrose per kg diet was replaced by D-tagatose (test group). After 18 d, the pigs were killed and the gastrointestinal contents removed for analysis. The digestibility of D-tagatose was 25.8 [+ or -] 5.6% in the distal third of the small intestine. The small intestinal digestibilities of dry matter (86.9 [+ or -] 1.3 vs. 92.9 [+ or -] 0.9%), gross energy (74.4 [+ or -] 1.6 vs. 80.7 [+ or -] 1.8%) and sucrose (90.4 [+ or -] 2.5 vs. 98.0 [+ or -] 0.5%) were lower (P < 0.05) in the pigs fed D-tagatose. Digestibilities of starch, protein and fat did not differ between groups. D-Tagatose, sucrose and starch were fully digested in the large intestine. The fecal digestibilities of energy, dry matter and fat did not differ between the two groups, whereas D-tagatose reduced the fecal digestibility of protein (91.1 [+ or -] 0.6 vs. 93.5 [+ or -] 0.7%, P < 0.05). D-Tagatose served as a substrate for the microbiota in the cecum and proximal colon as indicated by a reduced pH, and a greater ATP concentration, adenylate energy charge (AEC) ratio and concentration of short-chain fatty acids. In particular, the increase in the concentrations of propionate, butyrate and valerate suggests possible health benefits of this monosaccharide. KEY WORDS: sweetener; sugar; digestibility; fermentation; pigs; D-tagatose

Changes in the amount of adenosine triphosphate (ATP) and related compounds were observed including free amino acids, organic acids, betaines, glycogen and glycolytic metabolites in the Japanese baking scallop during refrigerated storage at 0-5 deg C. Large concentrations of free amino acids and glycine betaine were detected. The amounts of adenosine monophosphate, inosine and hypoxanthine increased during storage, but inosine monophosphate was not found. Hypoxanthine concentration is a better indicator of freshness than K value.

Nuclear magnetic resonance analysis shows that the monomeric subunit c of adenosine triphosphate (ATP) is a protein with two antiparallel helical segment folds in a homogeneous mixture of chloroform, methanol and water combined in a 4:4:1 ratio. The complete structure of subunit c cannot be determined because of significant resonance overlap which contains numerous hydrophobic amino acids. Subunit c is the transmembrane electrochemical H(super +) gradient that synthesizes ATP from ADP and P(sub i).

Gene expression of a membrane-bound Fo sector of the Escherichia coli F1Fo photon-translocating ATPase reacts to the changes in the metabolic conditions. The changes can be seen by observing the alterations in the subunit stoichiometry of the oligomeric Fo photon channel of the bacterium. Results revealed that nonfermentable carbon source alters the expression of Fo genes which can be traced in the transcriptional and translational lacZ fusions to the promoter.

The synthesis of Pseudomonas fragi's adenosine 5'-tetraphosphate and adenosine 5'-pentaA from an adenosine triphosphate and tetrapolyphospahte was broken down by acyl coenzyme A synthetase. The acyl coenzyme synthetase seemed similar to luciferase which is an enzyme that can catalyze the transfer of a nucleoside polyphosphate. Results of the experiment further supported the ability of such a synthetase to break down adenosine triphosphate synthesis.

The Escherichia coli Hsp40 DnaJ and Hsp70 DnaK cooperate in the binding of proteins at intermediate stages of folding, assembly, and translocation across membranes. Binding of protein substrates to the DnaK C-terminal domain is controlled by ATP binding and hydrolysis in the N-terminal ATPase domain. The interaction of DnaJ with DnaK is mediated at least in part by the highly conserved N-terminal J-domain of DnaJ that includes residues 2-75. Heteronuclear NMR experiments with uniformly 15N-enriched DnaJ2-75 indicate that the chemical environment of residues located in helix II and the flanking loops is perturbed on interaction with DnaK or a truncated DnaK molecule, DnaK2-388. NMR signals corresponding to these residues broaden and exhibit changes in chemical shifts in the presence of DnaK(MgADP). Addition of MgATP largely reversed the broadening, indicating that NMR signals of DnaJ2-75 respond to ATP-dependent changes in DnaK. The J-domain interaction is localized to the ATPase domain of DnaK and is likely to be dominated by electrostatic interactions. The results suggest that the J-domain tethers DnaK to DnaJ-bound substrates, which DnaK then binds with its C-terminal peptide-binding domain.

To investigate the mechanism of SWI/SNF action, we have analyzed the pathway by which SWI/SNF stimulates formation of transcription factor-bound nucleosome core complexes. We report here that the SWI/SNF complex binds directly to nucleosome cores and uses the energy of ATP hydrolysis to disrupt histone/DNA interactions, altering the preferred path of DNA bending around the histone octamer. This disruption occurs without dissociating the DNA from the surface of the histone octamer. ATP-dependent disruption of nucleosomal DNA by SWI/SNF generates an altered nucleosome core conformation that can persist for an extended period after detachment of the SWI/SNF complex. This disrupted conformation retains an enhanced affinity for the transcription factor GAL4-AH. Thus, ATP-dependent nucleosome core disruption and enhanced binding of the transcription factor can be temporally separated. These results indicate that SWI/SNF can act transiently in the remodeling of chromatin structure, even before interactions of transcription factors.

A study was conducted to examine the importance of the adenosine triphosphate binding sites of yeast 3-phosphoglycerate kinase and glycerol kinase. The 12 isomers of monoammine chromium(III) adenosine triphosphate were utilized and their inhibitions were compared. Results revealed that the side around the coordination sphere in hexokinase, which exhibited similarity with 3-phosphoglycerate kinase, was structurally related with glycerol kinase.

A study was conducted on the transience that is observed during the regulation of energy transfer in the ATP sulfurylase-GTPase system. The findings indicate that Pi binding directs the system through the coupled mechanism and that the mass ratio of the activated sulfate (APS) reaction can be tuned by adjusting flux through the coupled and uncoupled pathways. Moreover, this coupling mechanism provides an approach for controlling the quantity of chemical potential transferred to the APS reaction.

A study was conducted on the role of Escherichia coli single-strand DNA binding protein (SSB) in the synthesis of primer RNA (pRNA) catalyzed by E coli primase on the SSB-coated phase G4oric template. The findings indicate that ATP cross-linked to both primase and SSB could be equally utilized as initiating nucleotide for pRNA synthesis. Moreover, it is possible that SSB plays a key role in the initiation of pRNA synthesis in this system.

A minimal kinetic and thermodynamic model was developed to elucidate the mechanism of action of the DEAD box family of proteins. The eIF4A enzyme's affinity for ssRNA was found to be regulated by the binding of ADP*Mg2+ and ATP*-Mg2+* On the other hand, the value E.ATP complex's affinity for ssRNA is around 40 times more compared to the E.ADP's. The results further revealed that neither hydrolysis nor ATP binding is needed in the binding process of single-stranded RNA.

Adenosine triphosphate (ATP) and the protein components of the spliceosome play an important role in RNA rearrangements. ATPases unwind short RNA duplexes by functioning as a nonprocessive motor in splicing proofreadng steps. The spliceosome rearranges in a highly ordered and stepwise manner wherein many of the assembly steps relate to changes in RNA:RNA interactions. These interactions are depicted by powerful approaches, including phylogenetics, genetics and photochemical cross-linking procedures.

Research was conducted to study the effects of keratinocyte growth factor on alveolar epithelial cell active ion transport and on rat epithelial Na channel subunit and Na+-K+-adenosinetriphosphatase subunit isoform expression. Alveolar type II cells were determined from adult male Sprague-Dawley rats. Results suggested that the upregulation of either Na pump and chanel activities may result in a net increase in transepithelial Na transport.

A study was conducted on a binding site for ATP in the extracellular region of the Beta-subunit of the nicotinic acetylcholine receptor from Torpedo marmorata. The findings suggest that this purine nucleotide may act as a modulatory ligand of nicotinic acetylcholine receptors. Moreover, the results suggest the existence of 'chemical networks' that overlay the cellular networks typical for nervous systems.

The importance of GroES on cooperativity in ATP hydrolysis by (GroEL) was determined through analyses of sigmoidal kinetics. Results have shown that the GroES mediated the T to R transition of the GroEL ring distal to GroES in 1:1 GroEL-GroES complexes. The transition allowed for a better transmission of the protein messages release from ternary trans complexes. The mechanism was suggested to have assisted the folding of relatively large proteins that cannot form cis ternary complexes.

Extracellular ATP (adenosine triphosphate) draws a vigorous change in the concentration of intracellular Ca(2+) in fura-2-loaded mouse thymocytes. Most thymocytes exposed to extracellular ATP showed a biphasic rise in intracellular Ca(2+). Intracellular Ca(2+) rose slowly at first to a mean value of 260 nM after 163 s and then increased rapidly to a high level of 735 nM. Results indicate that thymocytes vary in sensitivity to extracellular ATP depending upon the degree of maturation which suggests that extracellular ATP may be involved in processes that control cellular differentiation within the thymus.

The role of the NADH/NAD+ ratio in the control shift from homolactic to mixed-acid metabolism was examined using Lactococcus lactis subsp. lactis NCDO 2118. The study revealed that the shift was directly correlated to the flux through glycolysis as shown by the sugar composition rates. The resulting gain in adenosine triphosphate was due to the increased acetate production during mixed-acid fermentation. This enables the growth on lactose to create a value close tro galactose.

Chaperonins are essential for the folding of proteins in bacteria, mitochondria, and chloroplasts. We have functionally characterized the yeast mitochondrial chaperonins hsp60 and hsp10. In the presence of ADP, one molecule of hsp10 binds to hsp60 with an apparent [K.sub.d] of 0.9 nM and a second molecule of hsp10 binds with a [K.sub.d] of 24 nM. In the presence of ATP, the purified yeast chaperonins mediate the refolding of mitochondrial malate dehydrogenase. Hsp10 inhibits the ATPase activity of hsp60 by about 40%. Hsp10(P36H) is a point mutant of hsp10 that confers temperature-sensitive growth to yeast. Consistent with the in vivo phenotype, refolding of mitochondrial malate dehydrogenase in the presence of purified hsp10(P36H) and hsp60 is reduced at 25 [degrees] C and abolished at 30 [degrees] C. The affinity of hsp10(P36H) to hsp60 as well as to Escherichia coli GroEL is reduced. However, this decrease in affinity does not correlate with the functional defect, because hsp10(P36H) fully assists the GroEL-mediated refolding of malate dehydrogenase at 30.sub.C. Refolding activity, rather, correlates with the ability of hsp10(P36H) to inhibit the ATPase of GroEL but not that of hsp60. Based on our findings, we propose that the inhibition of ATP hydrolysis is mechanistically coupled to chaperonin-mediated protein folding.

Phase contrast and fluorescence microscopy were utilized to analyze the importance of P2Z/P2X sub(7) receptor for extracellular ATP in J774 macrophage cell clones. Results obtained show that P2Zhyper macrophages become susceptible to lysis and ATP-mediated cell death. The P2Zhyper clones were shown to undergo fusion prior to formation of multinucleated giant cells, confirming the involvement of the receptor in macrophage fusion.

A study compared the kinetics of phosphorylation over a wide range of deoxycytidine concentrations with either adenosine triphosphate or uridine triphosphate as phosphate donor. It also examined the kinetic mechanism for deoxycytidine was also analyzed and the true phosphate donor, uridine triphosphate. Findings demonstrate that both the kinetic behavior at high deoxycytidine concentrations and the preferred reaction sequence differ with uridine triphosphate compared to adenosine triphosphate as the phosphate donor.

The mechanisms involved in the adenosine triphosphatase (ATPase) reaction of DNA gyrase and the 43 kilodalton (kDa) domain of GyrB were analyzed by utilizing thiophosphoryl ATP analogs. Analysis of the molecular mechanisms mediating the coupling between nucleotide hydrolysis and DNA supercoiling indicated the absence of a metal ion-dependent reversal of diastereoselectivity. Furthermore, metal ion coordination mediated the ability of ATPalphaS and ATPbetaS to act as substrates for DNA gyrase and the 43 kDa GyrB protein.