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)

An ATPase stimulated by HCO - ions and other oxybases and inhibited by SCN- has been found in main excretory duct of rat submaxillary gland, a tissue, capable of actively secreting HCO - 3 ions. No such ATPase was found in the rabbit duct, which normally does not secrete HCO - 3. The HCO - 3 ATPase was localized in the plasma membrane fraction of the homogenate, as evidenced by the marker 5'-nucleotidase. The activities of the HCO - 3 ATPase increased in metabolic alkalosis and decreased in metabolic acidosis in parallel to secretion of HCO - 3 and K+ ions by the duct epithelium. These findings provide further evidence that the membrane-bound HCO - 3 ATPase is involved in active H+/HCO - 3 transport.
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PMID:H+ transport and membrane-bound HCO - 3 ATPase in salivary duct epithelium. 0 8

An HCO-3-activated and SCN--inhibited ATPase (ATP phosphohydrolase, EC 3.6.1.3) found in homogenates of intestinal mucosa of the eel was solubilized by Triton X-100. Optimal HCO-3-concentration and pH for the enzyme were 25 mM and 8.7, respectively. HCO-3-ATPase activity in both homogenate and solubilized preparations increased after seawater adaptation. This adaptive increase in enzyme activity was also observed in the gills and the kidney. The HCO-3-ATPase seems to be related to transport mechanisms, especially for Cl-, in osmoregulatory surfaces of the eel.
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PMID:HCO-3-activated adenosine triphosphatase in intestinal mucosa of the eel. 0 50

An ATPase stimulated by HCO-3ions and other oxybases and inhibited by SCN- has been found in main excretory duct of rat submaxillary gland, a tissue, capable of actively secreting HCO-3ions. No such ATPase was found in the rabbit duct, which normally does not secrete HCO-3. The HCO-3ATPase was localized in the plasma membrane fraction of the homogenate, as evidenced by the marker 5'nucleotidase. The activities of the HCO-3ATPase increased in metabolic alkalosis and decreased in metabolic acidosis in parallel to secretion of HCO-3 and K+ ions by the rat salivary duct epithelium. In renal cortex tissue, where HCO-3 is actively reabsorbed respectively H+ is secreted, there was also found a parallel change in the activity of the HCO-3ATPase and the rate of active H+ secretion. These findings provide further evidence that the membrane-bound HCO-3ATPase is involved in active H+/HCO-3 transport. The HCO-3ATPase is not only stimulated by HCO-3 but also by other non transportable oxybases, a finding which indicates H+ rather than HCO-3 being the actively transported component of the buffer system. Small concentrations of K+ ions decrease the Km for HCO-3 and thus yield stimulation of the HCO-3-ATPase. Thport changing in parallel with that of H+/HCO-3 may be taken as indicative for a coupled K+-H+-exchange mechanism to which the HCO-3ATPase is linked.
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PMID:The role of HCO3-stimulated ATPase in buffer transport. 1 63

Differential and density gradient centrifugation were used to prepare a vesicular membrane fraction from hog gastric mucosa enriched 17-fold with respect to cation-activated ATPase and 5'-AMPase. Fractionation of the gradient material by free flow electrophoresis resulted in a fraction 35-fold enriched in cation-activated ATPase and essentially free of 5'-AMPase and Mg2+ATPase. The addition of ATP to either fraction resulted in H+ uptake and Rb+ efflux. The ionophoric and osmotic sensitivity showed that these ion movements were due to transport rather than binding. The cation selectivity sequences, substrate specificities and action of inhibitors indicated that the transport was a function of K+ATPase activity. The characteristics of the ATP-dependent enhancement of SCN- uptake and 8-anilinonapthalene-1-sulfonate fluorescence in the presence of valinomycin and the action of ionophores and lipid-permeable ions suggested that the energy dependent K+:H+ exchange was effectively nonelectrogenic. Thus these vesicles contain a nonelectrogenic (H+ + K+)-ATPase, hence acid secretion by the stomach is probably due to an ATP-dependent H+ + K+ exchange.
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PMID:A nonelectrogenic H+ pump in plasma membranes of hog stomach. 1 75

It has been proposed (Slayman, C.L., Long W.S., and Lu, C.Y.-H. (1973) J. Membr. Biol. 14, 305--338) that in Neurospora crassa, a plasma membrane ATPase functions to pump H+ ions out of the cell, thereby generating an electrochemical gradient that can drive transport processes. Using the concanavalin A method of Scarborough (Scarborough G.A. (1975)J. Biol. Chem. 250, 1106--1111), we have prepared plasma membranes of Neurospora and have deomonstrated that they do contain a distinct ATPase activity with the following properties. It has a pH optimum of 6.0, is highly specific for ATP (hydrolyzing other nucleoside triphosphates less than 6% as rapidly), requires Mg2+ at concentrations approximately equimolar to the concentration of ATP, is weakly stimulated by certain monovalent cations (K+ and NH4+) and anions (SCN- and acetate), is inhibited by N,N'-dicyclohexylcarbodiimide, but is not affected by oligomycin or ouabain. The plasma membrane fraction also contains residual mitochondrial contamination, which can be determined quantitatively by assaying oligomycin-sensitive ATP-ase activity, at pH 8.25, and succinic dehydrogenase activity.
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PMID:Characterization of plasma membrane adenosine triphosphatase of Neurospora crassa. 1 97

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

An ATPase is demonstrated in plasma membrane fractions of goldfish gills. This enzyme is stimulated by Cl- and HCO-3, inhibited by SCN-. Biochemical characterization shows that HCO-3 stimulation (Km = 2.5 mequiv./l) is specifically inhibited in a competitive fashion by SCN- (Ki = 0.25 mequiv./l). This residual Mg2+-dependent activity is weakly affected by SCN-. In the microsomal fraction chloride stimulation of the enzyme occurs in the presence of HCO-3 (Km for chloride = 1 mequiv/l); no stimulation is observed in the absence of HCO-3. Thiocyanate exhibits a mixed type of inhibition (Ki = 0.06 mequiv./l) towards the Cl- stimulation of the enzyme. Bicarbonate-dependent ATPase from the mitochondrial fraction is stimulated by Cl-, but this enzyme has a relatively weak affinity for this substrate (Km = 14 mequiv./l).
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PMID:A Cl-/HCO-3-ATPase in the gills of Carassius auratus. Its inhibition by thiocyanate. 1 77

The activity of ATPase was studied in highly purified rat liver and thymus cell nuclei, HCO3-, CO3(2-) and SO3(2-) stimulated nuclear ATPase in 1.5--2 times. HSO3- did not affect the enzyme activity, and NO3-, J-, ClO4-,F- and SCN- inhibited it. Bicarbonate increased V and decreased Ka for ATP. SCN- inhibited HCO3--ATPase activity non-competitively with respect to HCO3-. Mg2+-ATPase activity did not depend on pH, and HCO3-component of the activity was decreased under alkaline pH. Mg2+, Mn2+ and Co2+ increased the initial ATPase activity and helped its stimulation with HCO3-. Ba2+, Ni2+ and Zn2+ inhibited the ATPase activity, and Ca2+ did not affect it, Nuclear ATPase is sensitive to 2,4-dinitrophenol and DNAase. It is suggested that cell nuclei have their own H+-ATPase differing for some characteristics from mitochondrial H+-ATPase.
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PMID:[Investigation of adenosinetriphosphatase activity of rat liver and thymus cell nuclei]. 3 23

The effects of ATP, Mg(2+), and various agents on pH gradient, membrane potential, and catecholamine transport across membranes of intact bovine chromaffin vesicles were investigated. Methylamine and thiocyanate (SCN(-)) distributions across the vesicle membrane were used to estimate the H(+) concentration gradient and membrane potential, respectively. The H(+) concentration ratio (intravesiculanmedium) equals 16 when the medium pH is 6.9 and is unaltered by ATP and Mg(2+). In the absence of ATP and Mg(2+), the steady-state intravesicular S(14)CN(-) concentration is lower than the medium concentration. ATP and Mg(2+) cause an increased influx and a decreased efflux of SCN(-) that results in SCN(-) being concentrated in the vesicles 6- to 8-fold over the medium. The findings are consistent with an ATP,Mg(2+)-induced potential of approximately 50 mV (intravesicular side positive). Carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), a H(+) translocater, and N-ethylmaleimide (NEM), a sulfhydryl reagent, decrease the SCN(-) ratio and, thus, the membrane potential in the presence of ATP and Mg(2+). They have no effect on the H(+) concentration gradient. The rate of catecholamine uptake into vesicles is increased 4- to 6-fold by ATP and Mg(2+). The ATP,Mg(2+)-stimulated uptake is inhibited by FCCP and NEM over the same concentration ranges that reduce the SCN(-) distribution (membrane potential). FCCP increases and NEM decreases vesicular membrane ATPase activity. Thus, catecholamine uptake is correlated to an inside-positive membrane potential, and not to ATPase activity. If catecholamine uptake is coupled to membrane potential, then a charged species must be involved in the transport mechanism. Reserpine and rotenone inhibit catecholamine influx but have no effect on the H(+) electrochemical gradient; they probably act at a step before coupling to the membrane potential (or the H(+) electrochemical gradient). Atractyloside, an inhibitor of nucleotide transport, has no effects on catecholamine transport or the H(+) electrochemical gradient.
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PMID:Evidence that catecholamine transport into chromaffin vesicles is coupled to vesicle membrane potential. 3 85

Only in SW fish, Prolactin (PRL) treatment increased natremia and especially chloremia. In gill, the decreases of Mg++ ATPase and SCN-sensitive, HCO3-ATPase observed in control fish after transfert from SW to FW, were more marqued in FW 8 days PRL treated fish. Renal enzyme activities were not affected by PRL treatment. If PRL treatment acts effectively on branchial ionic extrusion mechanisms, the connection between HCO3-ATPase anc Cl--transport remains to be elucidated. These results can be explained with reference to existence of two chloride-cell types.
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PMID:[Effects of prolactin on chloremia and HCO3 dependant ATPase activities in kidney and gill of grey mullet, chelon Labrosus, during fresh water adaptation (author's transl)]. 3 24


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