Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The isomeric forms of bovine S-100a and S-100b have been shown to stimulate ATPase activities in fractions enriched in myelin and mitochondria isolated from the Gerbil brain and for S-100b more effectively than for calmodulin in erythrocytes or skeletal muscle. In the presence of Ca2+, S-100a produced a slight increase of ATPase activity in the mitochondrial fraction. However, S-100b in the presence of Zn2+ almost doubled the ATPase activity in brain myelin. S-100a, or S-100b, with or without Ca2+ and Zn2+ respectively, had no effect on the ATPase activity in mitochondria of the Gerbil liver. The observations may indicate a "second messenger" role for S-100b in the presence of Zn2+ in the Schwann cell.
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PMID:Modulation of ATPase activities in the central nervous system by the S-100 proteins. 253 Apr 65

[3H]LY186126, an analogue of the cardiotonic agent indolidan, was shown to bind reversibly and with high affinity (Kd = 4 nM) to a single class of binding sites within canine myocardial vesicles. Binding site density measured in various cardiac membrane fractions correlated well with Ca2+-ATPase activity (r = 0.94; p less than 0.01), but not with Na+,K+-ATPase or azide sensitive ATPase, indicating a localization of these sites within sarcoplasmic reticulum membranes. Divalent cations were required for binding and displayed the following order of activation: Zn2+ greater than Mn2+ greater than Mg2+ greater than Ca2+. Differential activation of [3H]LY186126 binding by various divalent cations was due to alterations in binding site density, rather than affinity. cGMP and selective inhibitors of type IV membrane-bound phosphodiesterase (SR-PDE), for example, indolidan, milrinone, imazodan, and enoximone, selectively displaced bound [3H]LY186126 caffeine, theophylline, and rolipram were relatively impotent as inhibitors of radiolabel binding. Kd values from displacement curves were highly correlated with IC50 values for inhibition of SR-PDE (r = 0.92; p less than 0.001). In addition, Kd values correlated well with published ED50 values for increases in cardiac contractility in pentobarbital-anesthetized dogs (r = 0.94; p less than 0.001). The results support the hypothesis that [3H]LY186126 labels the pharmacological receptor for the class of positive inotropic agents characterized as isozyme-selective phosphodiesterase inhibitors. Furthermore, the data suggest that the identity of the site labeled by [3H]LY186126 is SR-PDE, the type IV isozyme of cardiac phosphodiesterase located in the sarcoplasmic reticulum.
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PMID:Characterization and pharmacological relevance of high affinity binding sites for [3H]LY186126, a cardiotonic phosphodiesterase inhibitor, in canine cardiac membranes. 254 18

Two experiments were carried out in which rats were offered diets containing different amounts and types of dietary fibre, i.e. commercial stock diet and three semi-purified diets containing no fibre, 200 g wheat bran or 200 g pectin/kg. Dietary inclusion of fibre, and especially pectin, stimulated large bowel fermentation, as indicated by caecal hypertrophy and reduced caecal pH. After 3 weeks, mucosal:serosal zinc transfer and Zn accumulation by tissue were measured using the everted-gut-sac technique. In Expt 2, incubations were carried out in the presence and absence of 0.25 mM-ouabain to assess the importance of transfer by Na+,K+-ATPase-dependent mechanisms, and some observations on glucose transport were also made. Ouabain reduced rates of transfer of both Zn and glucose and also tissue Zn accumulation. There were no significant differences in rates of Zn transfer by everted sacs from duodenal, ileal and colonic sites, but accumulation of Zn by tissue was a more important fate than transfer across the serosal surface, and accumulation by duodenal tissue was approximately twice as great as by other tissues. Mucosal:serosal transfer of glucose by ileal tissue was much more sensitive to ouabain than was Zn transfer. Previous diet appeared to alter the capacity of the intestinal tissue to transfer Zn, with the highest rates of transfer being by colonic tissue from pectin-fed rats.
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PMID:Intestinal zinc transfer by everted gut sacs from rats given diets containing different amounts and types of dietary fibre. 255 62

This study concerns the properties of rapid K+ and Cl transport pathways that are present in the (H+ + K+)-ATPase membrane from stimulated, and secreting, gastric oxyntic cells. Ion permeabilities in the isolated stimulation-associated vesicles were monitored via the rates of H+ efflux under conditions of exclusive H+/K+ counterflux or H+ - Cl co-efflux, as well as by comparison of equilibration rates for 86Rb and 36Cl under conditions of equilibrium exchange and unidirectional salt flux. These latter studies suggest that Rb+ and Cl pathways are conductive and independent. In spite of the functional independence of the ion pathways, several divalent cations inhibit Rb+ and Cl isotopic exchange as well as the H+ efflux that is dependent on either K+ or anion (Cl, SCN, NO2) fluxes. Zn2+ is the more potent inhibitor, reducing by 50% the sensitive component of K+, Cl, and NO2 fluxes at about 20 microM; Mn2+ has a similar effect at 200 microM. Ni2+ and Co2+ were roughly equipotent to Mn2+ while Mg2+ and Ca2+ had no inhibitory effect. These results suggest that the stimulation-induced permeabilities, while functioning independently, may be physically linked, i.e., residing within a single entity. In similar studies carried out in (H+ + K+)-ATPase vesicles obtained from nonstimulated cells, no vestiges of sensitivity to the inhibitory divalent cations could be detected. The implications of these findings for the physiology of the oxyntic cell in the context of a model for membrane fusion are discussed.
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PMID:K+ and Cl- conductances in the apical membrane from secreting oxyntic cells are concurrently inhibited by divalent cations. 258 27

Prolonged cadmium exposure has been associated with proteinuria, calcuria and loss of calcium from bones in humans. Previous studies have shown that kidney uptake of cadmium in vivo results from proximal tubule absorption of the circulating cadmium metallothionein complex (CdMT), and intracellular release of the Cd2+ ion prior to induction of renal metallothionein. Parenteral administration of CdMT has been found to selectively damage the proximal tubule cell lysosome system with development of a tubular proteinuria pattern similar to that observed under chronic exposure conditions. The present studies also demonstrate a concomitant calcuria but no changes in the excretion of other electrolytes or glucose using this model. These marked changes in renal calcium metabolism occurred in the absence of mitochondrial damage, changes in total, Na/K or Mg-stimulated ATPase activities, renal ATP levels, membrane 45Ca2+ transport or overt tubule cell necrosis during an 8 hour period following CdMT injection. Proteinuria and calcuria were prevented by prior zinc induction of the renal MT pool. Data from these studies indicate that renal proximal tubule cell uptake and degradation of the circulating CdMT complex produces both a marked proteinuria and calcuria. The calcuria does not appear to stem from changes in renal energy metabolism or membrane transport of this element but is probably a secondary result of calcium binding to excreted proteins which are increased in urine to a similar extent. The studies also suggest that zinc status and maintenance of the renal ZnMT pool may play an important role in regulating cadmium-induced renal proteinuria and calcuria by preventing Cd2+ perturbation of the proximal tubule cell lysosome system.
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PMID:Mechanism of cadmium-metallothionein-induced nephrotoxicity: relationship to altered renal calcium metabolism. 282 68

Previous investigation showed two distinct ATP-dependent proton-transporting systems in microsomal vesicle from radish seedlings, one inhibited by vanadate and one inhibited by NO-3. On the bases of the effects of these inhibitors we could discriminate two distinct ATPase activities in the same material. The NO-3 sensitive activity was separated from the vanadate-sensitive activity and partially purified by a single-step chromatographic method, which lead to approx 35-fold purification from the microsomes and to a specific activity of 2.3 mumol Pi X min-1 X mg protein-1, at 30 degrees C. The partially purified activity was specific for ATP, some activity being observed toward GTP, and even less toward CTP, UTP and ITP. No significant Pi hydrolysis was found with ADP, AMP, p-nitrophenylphosphate and glucose 6-phosphate. ADP but not AMP was inhibiting in the presence of ATP. The activity was dependent on divalent cations in the order of preference: Mg2+ greater than Mn2+ greater than Co2+ greater than Ca2+ greater than Zn2+. The activity was unaffected by monovalent cations, strongly activated by Cl-, inhibited by 90% by 50 mM NO-3, virtually unaffected by oligomycin and NaN3. At least 90% of the activity was abolished in the presence of each: 10 microM N,N'-dicyclohexylcarbodiimide, 10 microM erythrosin B, 10 mu mersalyl, 100 microM trimethyltin, 100 microM diethylstilbestrol, 100 microM N-ethylmaleimide. No inhibition has been found in the presence of Ca2+, at a concentration blocking the vanadate-sensitive activity. Nigericin, gramicidin and carbonylcyanide p-trifluoromethoxyphenylhydrazone stimulated the activity of this preparation after it was incubated in the presence of sonicated phospholipids, suggesting the capacity of the ATPase to function as a H+-transporting system. All characteristics mentioned were closely similar to those described in the vacuolar ATPases.
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PMID:Partial purification and characterization of an anion-activated ATPase from radish microsomes. 285 45

The oxidants of the SH groups (o-iodozobenzoate, oxidized glutathione, etc.) and the divalent cations of some metals (Zn2+ and Cd2+) significantly slow down the rate of inactivation by the protein inhibitor of the isolated F1-ATPase and ATPase in submitochondrial particles. Modification of SH groups in the ATPase does not change the rate of inactivation but completely prevents the effect of oxidants.
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PMID:The oxidation of sulfhydryl groups in mitochondrial F1-ATPase decreases the rate of its inactivation by the natural protein inhibitor. 286 62

The secondary transport systems of the yeast vacuolar membrane have been investigated by the method of radioactive isotopes [( 14C]arginine); activation of H+-ATPase by cations (Cat+), when the enzyme is under H+ control and measurement of changes in the proton gradient (delta pH) and membrane potential (Em) due to the supposed substrates of the transporters. The main mechanism of cation transport across the yeast tonoplast is probably H+/Cat+ antiport. The apparent Km of antiporters for Ca2+, Mg2+, Mn2+, Zn2+ and Pi are 0.06, 0.3, 0.8, 0.055-0.17 and 1.5 mM, respectively.
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PMID:H+/ion antiport as the principal mechanism of transport systems in the vacuolar membrane of the yeast Saccharomyces carlsbergensis. 286 11

The antifungal antibiotic miconazole and the cationic dye ethidium bromide, both caused K+ efflux, membrane depolarization and intracellular acidification in the yeast Saccharomyces cerevisiae. Whereas miconazole inhibited the activity of the plasma membrane H+-ATPase, no such inhibition was observed using ethidium bromide at concentrations up to 600 microM. Low concentrations of both drugs caused marked stimulation of the energy dependent Ca2+ uptake. The extra Ca2+ taken up in the presence of the drugs was localized within the vacuoles, whereas K+ was lost mainly from the cytosolic pool. The ions Zn2+ and La3+ inhibited the effect of both drugs on the stimulation of Ca2+ uptake. The results indicated that both drugs caused an increase in the permeability of cell membranes to ions, leading to an increase in the influx of Ca2+ into the cytosol along its electrochemical gradient. Consequently, the concentration of Ca2+ within the cytosol increased and in turn led to the enhancement of Ca2+ uptake by the energy dependent vacuolar Ca2+ system, which functioned as a Ca2+ detoxification system.
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PMID:Mechanism of stimulation of Ca2+ uptake by miconazole and ethidium bromide in yeasts: role of vacuoles in Ca2+ detoxification. 287 Apr 12

The purified proton ATPase of chromaffin granules contains five different polypeptides denoted as subunits I to V in the order of decreasing molecular weights of 115,000, 72,000, 57,000, 39,000, and 17,000, respectively. The purified enzyme was reconstituted as a highly active proton pump, and the binding of N-ethylmaleimide and nucleotides to individual subunits was studied. N-Ethylmaleimide binds to subunits I, II, and IV, but inhibition of both ATPase and proton pumping activity correlated with binding to subunit II. In the presence of ADP, the saturation curve of ATP changed from hyperbolic to a sigmoid shape, suggesting that the proton ATPase is an allosteric enzyme. Upon illumination of the purified enzyme in the presence of micromolar concentrations of 8-azido-ATP, alpha-[35S]ATP, or alpha-[32P]ATP subunits I, II, and IV were labeled. However, at concentrations of alpha-[32P]ATP below 0.1 microM, subunit II was exclusively labeled in both the purified and reconstituted enzyme. This labeling was absolutely dependent on the presence of divalent cations, like Mg2+ and Mn2+, while Ca2+, Co2+, and Zn2+ had little or no effect. About 0.2 mM Mg2+ was required to saturate the reaction even in the presence of 50 nM alpha-[32P]ATP, suggesting a specific and separate Mg2+ binding site on the enzyme. Nitrate, sulfate, and thiocyanate at 100 mM or N-ethylmaleimide and 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole at 100 microM prevented the binding of the nucleotide to subunit II. The labeling of this subunit was effectively prevented by micromolar concentrations of three phosphonucleotides including those that cannot serve as substrate for the enzyme. It is concluded that a tightly bound ADP on subunit II is necessary for the activity of the enzyme.
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PMID:Nucleotide binding sites and chemical modification of the chromaffin granule proton ATPase. 288 30


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