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)

Exposure of rats to an ambient temperature of 5 degrees C for 4 to 6 weeks led to a 30 to 80 percent increase in the rate of oxygen consumption and a 50 percent increase in the rate of ethanol oxidation by liver slices, a 50 percent increase in mitochondrial alpha-glycerophosphate oxidase activity of liver, and a 100 percent increase in Na++K+-activated adenosine-triphosphatase, activity. Ouabain, an inhibitor of the Na++K+-activated adenosine-triphosphatase, completely blocked the extra respiration and ethanol oxidation. Dinitrophenol, which increases oxygen consumption and ethanol oxidation by liver slices from normal rats, was ineffective with slices from cold-exposed animals. Ethanol disappearance rate in vivo was also increased by cold acclimation, even though liver alcohol dehydrogenase activity was reduced. It is suggested that increased hydrolysis of ATP by the sodium pump system is responsible for the increased oxygen consumption and ethanol metabolism in the livers of cold-acclimated animals.
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PMID:Ethanol metabolism and liver oxidative capacity in cold acclimation. 12 85

[3H]Ouabain binding in frog and toad urinary bladder was investigated by short-circuit current (SCC), scintillation counting and autoradiographic techniques. SCC data and analysis of tissue digests following serosal exposure to ouabain showed that ouabain binding and inhibition of Na+ transport was completely reversible in toad bladder whereas, in frog bladder, [3H]ouabain was tightly bound and Na+ transport remained suppressed even after a 60-min washout. Mucosal exposure of frog bladder to [3H]ouabain or serosal exposure after preincubation with unlabeled ouabain led to a marked reduction in binding. Specificity of binding was assessed further by adjusting the concentration of certain (Na+ -K+)-ATPase ligands(K+, ATP) to levels known to reduce ouabain binding. High K+ concentrations and depletion of endogenous ATP by incubation under anoxic conditions resulted in a significant drop in [3H]ouabain binding. Autoradiographic analysis showed that grains are localized primarily to the basolateral plasma membranes of the granular cells, providing direct morphological evidence for the location of Na+ pumps at these sites. Although autoradiographs did not provide sufficient resolution to rule out unequivocally ouabain binding to the mitochondria-rich cell, morphological evidence suggests that grain densities are significantly higher between adjacent granular cells than between granular cell-mitochondria-rich cell interfaces.
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PMID:Localization of sodium pump sites in frog urinary bladder. 12 62

The chemical properties of two highly purified preparations of (sodium + potassium)-activated adenosine triphosphatase (NaK ATPase) and their subunits have been compared. One preparation is derived from the rectal gland of the spiny dogfish shark, Squalus acanthias and the other preparation is derived from the electric organ of the electric eel, Electrophorus electricus. Ouabain binding and phosphorylation from [gamma-32-P]ATP for both enzymes ranged from 4000 to 4300 pmol per mg of protein. This gives a stoichiometry for ouabain binding and phosphorylation of 1:1 for both enzymes. The molar ratios of catalytic subunit to glycoprotein was 2:1 for both enzymes, suggesting a minimum molecular weight of 250, 000, which agrees with the molecular weight obtained by radiation inactivation. Assuming that only one of the two catalytic subunits is phosphorylated and binds ouabain per (sodium + potassium)-activated adenosine triphosphatase molecule the data on phosphorylation and ouabain binding also give a molecular weight of 250, 000. The data on phosphorylatiion, ouabain binding, subunit composition, and molecular weight based on radiaion inactivation are thus all internally consistent. A technique has been developed for isolation of pure catalytic subunit and glycoprotein in good yields by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A variety of chemical studies have been carried out with the purified subunits. The amino acid composition of the catalytic subunit was different from that of the glycoprotein, but the amino acid composition of each of the two subunits was essentially the same for both species. However, the NH2-terminal amino acid for the catalytic subunit was alanine for the rectal gland enzyme and serine for the electric organ enzyme, suggesting some differencesin amino acid sequences for the two species. The NH2-terminal amino acid for the glycoprotein was alanine for the two species. The glycoproteins from both species contained the same carbohydrates but in quite differing amounts. The carbohydrates were glucosamine, sialic acid, fucose, galactose, mannose, and glucose. The release of all the sialic acid from the electric organ enzyme and the release of 40% of the sialic acid from the rectal gland enzyme did not affect (sodium + potassium)-activated adenosine triphosphatase activity. Both enzymes contained the following phospholipids, which accounted for 98 to 100% of the total phospholipid phosphorus: sphingomyelin, lecithin, phosphatidylserine, phosphatidylethanolamine, and phosphatidylinositol. With the exception of phosphatidylethanolamine, and phosphatidylinositol. With the exception of phosphatidylserine, the amount of any phospholipid per mg of enzyme as well as the total phospholipid content were quite different for the two enzymes.
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PMID:Molecular properties of purified (sodium + potassium)-activated adenosine triphosphatases and their subunits from the rectal gland of Squalus acanthias and the electric organ of Electrophorus electricus. 12 22

Ouabain, which inhibits specifically membrane-bound ATPase activity, also inhibits the establishment of the antiviral state induced by interferon. Once the antiviral state is established, ouabain is ineffective. This inhibitory effect is reversed by adding Na/K ions to the cells. On the contrary, interferon production is unaffected by the same concentrations of ouabain. It is of interest that in such interferon-yielding cells, ouabain decreases the antiviral state.
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PMID:Different effect of ouabain on the interferon production and action. 12 71

The purpose of this work was to test the previously suggested hypothesis that the inhibitory effect of ouabain on lactate production in human red cells is due to an interaction between phosphoglycerate kinase and (Na+ + k+)-activated adenosine triphosphatase (Na+,K+ATPase). An antibody to red cell phosphoglycerate kingase caused complete inhibition of the purified enzyme, whereas a portion of the phophoglycerate kinase activity of the red cell membranes was resistant to the antibody. When increasing amounts of the purified enzyme were added to the membranes, the antibody-resistant portion of the activity increased. The effects of the antibody and ouabain on lactate production from fructose-6,6-diphosphate in red cell hemolysates were studied. Ouabain, at a maximally effective concentration, produced about 30% inhibition of lactate formation. This value was doubled in the presence of the antibody. Red cell membranes, and rat brain Na+,K+-ATPase, did not catalyze the hydrolysis of 1,3-diphosphoglycerate. Ouabain did not affect the reactions of the Rapport-Luebering pathway of the red cells. These findings provide further support for the view that in red cells a membrane pool of phosphoglycerate kinase is oriented in the vicinity of Na+,K+-ATPase in a way that the product of each enzyme may be used as the immediate substrate of the other and that ouabain inhibits glycolysis by removing the regulatory effect of Na+,K+-ATPase on that portion of glycolysis which is channeled through this pool of phosphoglycerate kinase.
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PMID:Studies on the mechanism of inhibition of the red cell metabolism by cardiac glycosides. 12 26

Effects of some chemicals, which are known as inhibitors of Ca2+-dependent ATPases, on the water receptor of the frog tongue were examined by using single fungiform papilla preparations. When a sufficient amount of ruthenium red, quinacrine hydrochloride, ethacrynic acid or 2,4-dinitrophenol was added to the standard stimulating solution (5mM CaCl2+100 mM NaCl), which has been shown to stimulate sufficiently the water receptor of the frog tongue, no neural response was elicited. The concentrations necessary for 50% inhibition were approximately 3 X 10(-6)M for ruthenium red, 1 X 10(-5) M for quinacrine hydrochloride, 1 X 10 (-3) M for ethacrynic acid and 2 X 10(-4) M for 2,4-dinitrophenol. Organic mercurials, mersalyl acid and p-chloromercuribenzoic acid, had no effect on the nueral response, but repeated application of these chemicals led to a permanent depression in receptor activity. Ouabain had no effect on either the neural response or receptor activity. These observations indicate that the receptor molecule of the frog water receptor has a similar property to that of the Ca2+-dependent ATPase of red-cell membrane in respect to the susceptibility to inhibitors.
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PMID:Effects of ruthenium red, quinacrine hydrochloride, ethacrynic acid and 2,4-dinitrophenol on the water receptor of the frog tongue. 12 57

Rat kidneys perfused outside of the body with an artificial medium are able to increase their fractional excretion of potassium in response to a rising concentration of potassium in the medium but never show net secretion of potassium. By contrast, isolated perfused kidneys from chronically potassium-loaded rats regularly secrete potassium in excess of the amount filtered. Ouabain completely blocks the secretion of potassium by these isolated kidneys, suggesting that Na-K-ATPase mediates potassium secretion by potassium-adapted rats. Neither sodium deprivation, pretreatment with deoxycorticosterone, nor pretreatment with methylprednisolone prepared the kidney to secrete potassium, despite stimulation of Na-K-ATPase activity in cortex or outer medulla. Potassium loading was the only maneuver tested that increased the activity of Na-Katpase in the inner medulla (white papilla) and also produced potassium secretion by the isolated kidney. Surgical ablation of the papilla abolished the net secretion of potassium normally seen in perfused kidneys of potassium-adapted rats, thus underlining the importance of the papilla in the process of potassium adaptation.
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PMID:Potassium transport by the isolated perfused kidney. 12 66

The effects of diphenylhydantoin (DPH) and ouabain were studied in vitro on Mg-ATPase, Ca-ATPase and alkaline phosphatase (AlPase) in isolated brush borders from rat jejunum, and in vivo on intestinal calcium absorption. Vitamin D-deficient, -repleted and normal rats were used in this study. Repletion of deficient animals with vitamin D restored Ca-ATPase activity and AlPase activity partly. Ca-absorption was normalized by repletion with the vitamin. DPH greatly stimulated Ca-ATPase activity in vitro and Ca-absorption in vivo, but it inhibited AlPase activity. Mg-ATPase was not affected by vitamin D, nor by DPH. Ouabain had no consistent effect on any of the parameters studied. It was concluded that Ca-ATPase, and not AlPase, is involved in the transport of calcium through the jejunal microvillous membrane, and that DPH enhances Ca-absorption by activation of Ca-ATPase.
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PMID:Stimulation of vitamin D-dependent Ca-ATPase and of intestinal caldium absorption by diphenylhydantoin. 12 71

Ouabain binding capacity of cell membranes is directly related to (Na+ + K+)-ATPase activity. The extent of ouabain inhibition of (Na+ + K+)-ATPase is a measure of ouabain receptor sites occupied. Dissociation constants of the ouabain-receptor complexes are identical in all organs in a single species but vary among different species. K+ decreases the association rate constant of the ouabain receptor interaction without altering the dissociation rate constants. Titration of digoxin-inhibited (Na+ + K+)-ATPase from guinea pig heart with digoxin antibodies shows a reversal of the inhibition at lower antibody concentrations in the presence of K+ than in the absence of K+. It is concluded that digitalis intolerance in acute hypokalemia reflects the increased affinity of the cardiac glycoside receptor under these conditions.
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PMID:Cardiac glycoside receptor in potassium depletion. 12 57

1. The membrane perturbations induced by the interaction of the fluorescent probe 1-anilino-8-naphthalene sulfonate (ANS) with human red blood cells were studied. 2. ANS below 0.5 mM inhibits partially (20% maximum) the ouabain-insensitive Na+ and K+ influx and efflux. Above 0.5 mM ANS increases both Na+ and K+ leak fluxes. The increased cation leaks are larger for Na+ than K+. 3. The (Na+ +K+)-ATPase and ouabain-sensitive Na+ and K+ fluxes are inhibited by ANS. Ouabain-insensitive, Mg2+-dependent ATPase activity of ghosts is stimulated by [ANS] less than 0.3 mM and inhibited by [ANS] greater than 0.3 mM. 4. ANS also inhibits the Na+-dependent, ouabain-insensitive K+ influx that is inhibited by ethacrynic acid and furosemide. 5. Red cells become crenated with [ANS] less than 1 mM and sphere at [ANS] greater than 1 mM. In the former conditions hypotonic hemolysis is decreased whereas the latter increase osmotic fragility. 6. It is suggested that ANS expands the membrane asymmetrically by binding preferentially to the external membrane surface. 7. It is concluded that ANS is a general inhibitor of ion transport, particularly of those processes thought to involve facilitated-diffusion mechanisms. The increased cation leaks observed at high ANS concentrations may be related to prehemolytic membrane disruption. 8. The membrane perturbations caused by ANS are compared to those caused by other reversible inhibitors of anion exchange in red blood cells. Their possible modes of action are discussed.
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PMID:Asymmetric membrane expansion and modification of active and passive cation permeability of human red cells by the fluorescent probe 1-anilino-8-napththalene sulfonate. 12 20


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