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)

A vesicular microsomal fraction isolated from hog fundic mucosa demonstrates the capacity to take up equal amounts of RB+ and Cl-. The amount of the Rb+ uptake is sensitive to the extravesicular osmolarity, and rate of uptake is sensitive to temperature. 86Rb+ efflux is dependent upon the cation composition of the diluting solution. ATP, but not beta-gamma methylene ATP, induces a reversible efflux of 86Rb+ from loaded vesicles, and this is dependent upon a functional K+-ATPase. The ATP induced efflux is not affected by CCCP (carbonyl cyanide m-chlorophenylhydrazone) or TCS (tetrachlorosalicylanilide) nor by lipid soluble ions or valinomycin. Nigericin inhibits the efflux by 40%. Uptake of the lipid soluble ion 14C-SCN- has been demonstrated and is enhanced by ATP only in the presence of valinomycin. The results are consistent with a neutral or isopotential exchange of H+ for Rb+ mediated by K+-ATPase.
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PMID:Cation transport by gastric H+:K+ ATPase. 1 7

The uptake of proline and glutamine by cytochrome-deficient cells of Escherichia coli SASX76 grown aerobically on glucose or anaerobically on pyruvate was stimulated by these two substrates. Pyruvate could not stimulate transport in the glucose-grown cells. Uptake of these amino acids energized by glucose was inhibited by inhibitors of the Ca2+, Mg2+-stimulated ATPase such as DCCD, pyrophosphate, and azide, and by the uncouplers CCCP and 2,4-dinitrophenol. Glycerol (or glycerol 3-phosphate) in the presence of fumarate stimulated the transport of proline and glutamine under anaerobic conditions in cytochrome-deficient cells but not in membrane vesicles prepared from these cells although glycerol 3-phosphate-fumarate oxidoreductase activity could be demonstrated in the vesicle preparation. In contrast, in vesicles prepared from cytochrome-containing cells of E. coli SASX76 amino acid transport was energized under anaerobic conditions by this system. Inhibitors of the Ca2+, Mg2+-activated ATPase and uncoupling agents inhibited the uptake of proline and glutamine in cytochrome-deficient cells dependent on the glycerol-fumarate oxidoreductase system. Ferricyanide could replace fumarate as an electron acceptor to permit transport of phenylalanine in cytochrome-deficient or cytochrome-containing cells under anaerobic conditions. It is concluded that in cytochrome-deficient cells using glucose, pyruvate, or glycerol in the presence of fumarate, transport of both proline and glutamine under under anaerobic conditions is energized by ATP through the Ca2+, Mg2+-activated ATPase. In cytochrome-containing cells under anaerobic conditions electron transfer between glycerol and fumarate can also drive transport of these amino acids.
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PMID:Anaerobic transport of amino acids coupled to the glycerol-3-phosphate-fumarate oxidoreductase system in a cytochrome-deficient mutant of Escherichia coli. 13 Sep 24

The effect of CMNQ was studied on mitochondria isolated from S-180 ascites tumor cells. It was found that the primary metabolic event upon addition of CMNQ to S-180 mitochondria was a stimulation of oxygen uptake. The oxygen utilization rate was maximized at about 50 nmoles CMNQ/mg protein; at doses higher than this, inhibition of respiration was observed relative to the stimulation of respiration produced by CCCP. It was also up to 50 nmoles CMNQ/mg protein. S-180 ATPase activity is stimulated maximally by 125 nmoles CMNQ/mg protein; at doses higher than this, slight inhibition of the ATPase activity relative to the stimulation produced by CCCP is seen. In vivo treatment of CMNQ to tumor bearing animals leads to a significant reduction of in vitro S-180 cellular respiration rates. The data presented in this work coupled with previously published reports involving CMNQ support the proposal for a mitochondrial level of action for this bioreductive alkylating antineoplastic agent.
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PMID:Effects of the bioreductive alkylating agent 2,3-bis(chloromethyl)-1,4-naphthoquinone on coupled mitochondria isolated from sarcoma 180 ascites cells. 16 26

Mitochondria were isolated from Euglena gracilis strain Z by pressure-breakage of the cells and sucrose-cushion centrifugation. Multiple peaks (2-4) were observed in the rate of phosphorylation with Mg-ADP-phosphate concentration curves. The phosphorylative and oxidative activities were highest with NADH as the substrate, moderate with succinate, and lowest with glutamate. Inhibition of phosphorylation with 2,4-dinitrophenol and carbonyl cyanide, m-chlorophenylhydrazone gave sigmoidal concentration curves, with the extent of inhibition by DNP depending on the substrate used. Inhibition of phosphorylation by valinomycin, atractyloside, or carboxyatractyloside was only approximately 60%. Oligomycin inhibited phosphorylation in 2 phases at low and high concentrations; it inhibited Mg-ATPase in a sigmoidal fashion. Both phosphorylation and oxidation had discontinuities in Arrhenius plots at 34 C and 18 C. The relative Mg2+-dependent nucleoside triphosphatase activity was: 1 for ATP and GTP, 0.6 for ITP, 0.15 for CTP and UTP; with Ca2+ in place pf Mg2+ this activity was 0.35. Both DNP and CCCP stimulated the Mg-ATPase 50-200%. The optimal pH for the stimulation was approximately 7 regardless of the uncoupler used, and approximately 8 without the uncouplers. The few differences observed between mitochodria from Euglena and those from other sources are probably due to the fragmentation of the reticular mitochondrial structure during isolation and not to unique characteristics of these mitochondria.
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PMID:Some biochemical properties of mitochondria isolated from Euglena gracilis. 19 37

Hydrolysis of extramitochondrial ATP by coupled Zajdela hepatoma mitochondria is not stimulated by uncouplers of oxidative phosphorylation. The results of the present study show that the hydrolysis of intramitochondrial ATP in these mitochondria is stimulated by DNP and CCCP. It is proposed that the uncoupler insensitivity of ATPase in coupled Zajdela hepatoma mitochondria with exogenous ATP as a substrate result from an altered functional relationship between ATPase and ADP, ATP translocase.
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PMID:Mitochondrial adenosine triphosphatase of Zajdela hepatoma. III. Effect of uncouplers on the hydrolysis of intramitochondrial ATP. 20 77

Addition of glucose and other sugars to derepressed cells of the fungus Fusarium oxysporum var. lini triggered activation of the plasma membrane H(+)-ATPase within 5 min. Glucose was the best activator while galactose and lactose had a lesser effect. The activation was not prevented by previous addition of cycloheximide and it was fully reversible when the glucose was removed. The activation process in vivo also caused changes in the kinetic properties of the enzyme. The non-activated enzyme had an apparent Km of about 3.2 mM for ATP whereas the activated enzyme showed an apparent Km of 0.26 mM. In addition, the pH optimum of the H(+)-ATPase changed from 6.0 to 7.5 upon activation. The activated enzyme was more sensitive to inhibition by vanadate. When F. oxysporum was cultivated in media containing glucose as the major carbon source, enhanced H(+)-ATPase activity was largely confined to the period corresponding to the lag phase, i.e. just before the start of acidification of the medium. This suggests that the activation process might play a role in the onset of extracellular acidification. Addition of glucose to F. oxysporum var. lini cells also caused an increase in the cAMP level. No reliable increase could be demonstrated for the other sugars. Addition of proton ionophores such as DNP and CCCP at pH 5.0 caused both a large increase in the intracellular level of cAMP and in the activity of the plasma membrane H(+)-ATPase. Inhibition of the DNP-induced increase in the cAMP level by acridine orange also resulted in inhibition of the activation of plasma membrane H(+)-ATPase.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Glucose-induced activation of the plasma membrane H(+)-ATPase in Fusarium oxysporum. 132 95

Citrobacter diversus ATCC 27156 was able to grow by decarboxylation of malonate to acetate under strictly anaerobic conditions, in the presence of yeast extract. The growth yield, corrected for growth on yeast extract, was 2.03 g cell dry mass per mol malonate. The addition of malonate to ATP-depleted cell suspensions (less than 0.2 nmol ATP/mg cell protein) resulted in a rapid increase in cellular ATP levels to between 4.5 and 6.0 nmol/mg cell protein. Intact cells decarboxylated malonate at rates of up to 1.5 mumol/min.mg protein. Enzyme assays on malonate-grown cells indicated activation of malonate by an ATP-dependent ligase reaction and by CoA transfer from acetyl-CoA, followed by decarboxylation of malonyl-CoA to acetyl-CoA with subsequent recovery of the invested ATP by substrate level phosphorylation through the activity of acetate kinase. Net ATP synthesis is postulated to be mediated by gradient formation coupled to the decarboxylation of malonyl-CoA. The protonophore CCCP and H(+)-ATPase inhibitor DCCD significantly reduced cellular ATP levels, suggesting a role for proton gradients in the energy metabolism of this strain when growing an malonate. Inhibitors of sodium metabolism or ommission of sodium had no effect on ATP levels or malonate decarboxylation.
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PMID:Anaerobic malonate decarboxylation by Citrobacter diversus. Growth and metabolic studies, and evidence of ATP formation. 151 May 73

The effect of a protonophoric uncoupler (CCCP) on the different cellular compartments was investigated in yeast grown aerobically on lactate. These cells were incubated in a resting cell medium under three conditions; in aerobiosis with lactate or glucose or in anaerobiosis with glucose as energetic substrate. For each condition, in vivo 31P NMR was used to measure pH gradients across vacuolar and plasma membrane and phosphorylated compound levels. Respiratory rate (aerobic conditions) and TPP+ uptake were measured independently. Concerning the polyphosphate metabolism, spontaneous NMR-detected polyphosphate breakdown occurred, in anaerobiosis and in the absence of CCCP. In contrast, in aerobiosis, polyphosphate hydrolysis was induced by addition of either CCCP or a vacuolar membrane ATPase-specific inhibitor, bafilomycin A1. Moreover, polyphosphates were totally absent in a null vacuolar ATPase activity mutant. The vacuolar polyphosphate content depended on two factors: vacuolar pH value, strictly linked to the vacuolar H(+)-ATPase activity, and inorganic phosphate concentration. CCCP was more efficient in dissipating the proton electrochemical gradient across vacuolar and mitochondrial membranes than across the plasma membrane. This discrepancy can be essentially explained by a difference of stimulability of each proton pump involved. As long as the energetic state (measured by NDP + NTP content) remains high, the plasma membrane proton ATPase is able to compensate the proton leak. Moreover, this ATPase contributes only partially to the generation of delta pH. The maintenance of the delta pH across the plasma membrane, that of the energetic state, and the cellular TPP+ uptake depend on the nature of the ATP-producing process.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Differential sensitivity of the cellular compartments of Saccharomyces cerevisiae to protonophoric uncoupler under fermentative and respiratory energy supply. 183 54

Using the 'fusogen' polyethyleneglycol (PEG), Dawson et al. have concluded that both guanosine triphosphate (GTP)-induced calcium efflux and the enhancement of IP3-promoted calcium release from rat liver microsomal vesicles could be attributed to a GTP-dependent vesicle fusion. We have studied GTP-induced fusion of microsomal vesicles from rat exocrine pancreas using light scatter and fluorescence dequenching methods. In the presence of PEG (3%), GTP (10 microM) induced a decrease in light scatter and an increase in fluorescence in the fluorescence dequenching assay (GTP-effect) indicating fusion of the vesicles. Guanosine 5'-O-(3-thiotriphosphate) (10 microM) had no effect on its own and inhibited the GTP-induced signals. Preincubation of the vesicles with adenosine triphosphate (ATP) (4 mM) increased the GTP-effect by 80%, whereas bafilomycin B1, a specific inhibitor of vacuolar type H(+)-ATPases, and the protonophore CCCP (10 microM) inhibited only the ATP-dependent part of the GTP-effect. Inhibitors of the vacuolar type H(+)-ATPase, which are also SH-alkylating reagents such as N-ethylmaleimid (100 microM) and the tyrosine-, cysteine- and lysine-reactive reagent 7-chloro-4-nitrobenz-2-exa-1,3-diazole (10 microM), abolished the GTP-effect in the absence or presence of ATP. We conclude that GTP induces fusion of pancreatic microsomes which is increased by an H+ gradient established by a vacuolar type H(+)-ATPase.
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PMID:GTP-induced fusion of isolated pancreatic microsomal vesicles is increased by acidification of the vesicle lumen. 214 54

Energy coupling of L-glutamate transport in brain synaptic vesicles has been studied. ATP-dependent acidification of the bovine brain synaptic vesicles was shown to require CI-, to be accelerated by valinomycin and to be abolished by ammonium sulfate, nigericin or CCCP plus valinomycin, and K+. On the other hand, ATP-driven formation of a membrane potential (positive inside) was found to be stimulated by ammonium sulfate, not to be affected by nigericin and to be abolished by CCCP plus valinomycin and K+. Like formation of a membrane potential, ATP-dependent L-[3H]glutamate uptake into vesicles was stimulated by ammonium sulfate, not affected by nigericin and abolished by CCCP plus valinomycin and K+. The L-[3H]glutamate uptake differed in specificity from the transport system in synaptic plasma membranes. Both ATP-dependent H+ pump activity and L-glutamate uptake were inhibited by bafilomycin and cold treatment (common properties of vacuolar H(+)-ATPase). ATP-dependent acidification in the presence of L-glutamate was also observed, suggesting that L-glutamate uptake lowered the membrane potential to drive further entry of H+. These results were consistent with the notion that the vacuolar H(+)-ATPase of synpatic vesicles formed a membrane potential to drive L-glutamate uptake. ATPase activity of the vesicles was not affected by the addition of Cl-, glutamate or nigericin, indicating that an electrochemical H+ gradient had no effect on the ATPase activity.
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PMID:Energy coupling of L-glutamate transport and vacuolar H(+)-ATPase in brain synaptic vesicles. 214 57


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