Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sodium- and potassium-activated adenosine triphosphatase (NaK-ATPase) was purified from nasal salt glands of the duck (Anas platyrhynchos). Enzyme of specific activity 2,000 to 2,300 mumol of Pi/mg/hour was routinely obtained by sodium dodecyl sulfate treatment of a microsomal fraction of gland homogenate in the presence of 3 mM ATP followed by pelleting of the enzyme through a sucrose density gradient. Purified NaK-ATPase was stable for over 3 months at -20 degree. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration chromatography purified NaK-ATPase was shown to contain two polypeptide chains of molecular weight 94,000 and 60,000, the smaller of which was a glycoprotein. Purified enzyme of activity 2,300 mumol of Pi/mg/hour bound 3,600 pmol of ouabain/mg of enzyme protein. Reaction with [gamma-32P]ATP in the presence of Mg2+ and Na+ gave 7,025 pmol of acyl phosphate/mg of enzyme protein. The turnover number calculated from phosphorylation data was 5,460 min-1. Amino acid analysis of the polypeptide components of duck salt gland enzyme after separation by gel filtration chromatography in sodium dodecyl sulfate demonstrated strong compositional homology with highly purified NaK-ATPase preparations from other organs and species. The NH2-terminal amino acid of the 94,000-dalton component was glycine and of the 60,000-dalton component, alanine. With a combination of manual sequencing and automated Edman degradation, the NH2-terminal amino acid sequence of the 94,00-dalton catalytic subunit was found to be Gly-Arg-Asn-Lys-Tyr-Glu-Thr-Thr-Ala-()-Ser-Glu.
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PMID:Sodium- and potassium-activated adenosine triphosphatase of the nasal salt gland of the duck (Anas platyrhynchos). Purification, characterization, and NH2-terminal amino acid sequence of the phosphorylating polypeptide. 13 47

The synthesis of a 3beta-thiocyanatocardenolide is described. The compound exhibited about 0.1 times the cardiotonic effect of digitoxyigenin in the isolated frog heart preparation. At a dosage of 20 mg/kg in the intact rat, it elicited ECG changes similar to those seen with a 10-mg/kg dose of digitoxigenin. Studies also revealed the new cardenolide to be a reversible inhibitor of sodium- and potassium-activated adenosine triphosphatase.
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PMID:Thiocardenolides I: synthesis and biological actions of 3beta-thiocyanato-14beta-hydroxy-5beta-card-20(22)-enolide. 13 23

Purified (Na+, K+)-activated adenosine triphosphatase ((Na+, K+)-ATPase, ATP phosphohydrolase, EC 3.6.1.3) has been subjected to trypsin and chymotrypsin hydrolysis. The glycoprotein is much more resistant to proteolysis than the large chain. This differential susceptibility to proteolysis is not due to differences in the number of trypsin or chymotrypsin sensitive bonds because the two subunits are equally susceptible to proteolysis after isolation by preparative gel electrophoresis in sodium dodecyl sulfate. It is also not due to steric "shielding" of the glycoprotein by the large chain or its proteolytic products: (1) The rate of digestion of the glycoprotein is not increased after 90% of the large chain is digested. (2) The majority of the large chain peptides are released into the supernatant upon degradation. It is concluded that the greater resistance of the glycoprotein to proteolysis is due to its native conformation. In the absence of the large chain, the susceptibility of the glycoprotein to tryptic degradation by K+ and Na+. The evidence suggests that this decreased susceptibility was due to conformational changes in the glycoprotein. These specific ligand effects on proteolysis of the glycoprotein suggests that the glycoprotein may participate in Na+ and K+ binding by (Na+, K+)-ATPase.
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PMID:The susceptibility of the glycoprotein from the purified (Na+, K+)-activated adenosine triphosphatase to tryptic and chymotryptic degradation with and without Na+ and K+. 13 66

Analysis of sodium-22 binding to purified sodium + potassium ion-activated adenosine triphosphatase (Na+, K+)-ATPase reveals the presence of two classes of binding sites. The higher affinity site (Kd = 0.2 mM) binds 6 to 7 nmol of sodium per mg of protein. Pretreatment of (Na+, K+)-ATPase with ouabain blocks the binding of sodium to this higher affinity site. Neither heat-denatured enzyme nor phospholipids extracted from the (Na+, K+)-ATPase contain a ouabain-inhibitable, higher affinity sodium binding site. The ouabain enzyme complex therefore appears to contain altered binding sites for cations.
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PMID:Specific sodium-22 binding to a purified sodium + potassium adenosine triphosphatase. Inhibition by ouabain. 13 7

The polypeptide chain of the Ca2+-stimulated adenosine triphosphatase from sarcoplasmic reticulum has a molecular weight of 119 000+/-6500 on the basis of sedimentation equilibrium measurements in sodium dodecyl sulfate. The two primary fragments obtained by limited proteolysis each have within experimental error the same molecular weight, corresponding to one-half the molecular weight of the whole chain. Both fragments are eqaully resistant to complete denaturation by guanidine hydrochloride, a property characteristic of many intrinsic membrane proteins. This suggests that the native enzyme has two membrane-embedded halves, with an externally accessible link between them.
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PMID:Molecular weights and hydrophobicity of the polypeptide chain of sarcoplasmic reticulum calcium(II) adenosine triphosphatase and of its primary tryptic fragments. 13 15

Studies conducted into the activity of adenosine triphosphatase (ATPase) in homogenate of several tissues of sheep and against the background of pH 7.5 (tris-HCl buffer) have shown highest enzyme activity to develop in renal cortex and cerebral cortex followed, in declining order of quotation, by liver, myocardium, and mucous membrane of small intestine. ATPase activities were studied also in the presence of pH-values between 7.2 and 8.95 (tris-HCl buffer) and between 8.6 and 11 (piperazine buffer), with the pH optimum of ATPase in the above tissues having been found to lie at approximately 9.0. Different concentrations of Mg ions were added, and maximum ATPase activity of 2 mMol ATP was obtained by adding 2 mMol Mg. Decline in ATPase activity should be expected in the case of hypomagnesaemia. Addition of different concentrations of sodium and potassium ions gave in most of the tissues tested maximum activity in response to 10 mMol potassium and 68 mMol sodium. Na-K ATPase could be inhibited by oubain particularly in cerebral and renal cortex.
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PMID:[Activities and properties of adenosine triphosphatase (ATPase) in homogenates of renal cortex, liver, myocardium and small-intestine mucosa in sheep]. 13 80

1. The activities of some membrane-bound enzymes such as adenylate cyclase, Na+ + K+-stimulated adenosine triphosphatase (Na+ + K+-ATPase), Ca2+-stimulated ATPase and Mg2+-stimulated ATPase were examined in heart sarcolemmal fractions from control and cardiomyopathic hamsters at different stages of heart failure. 2. The basal adenylate cyclase activity in sarcolemma from cardiomyopathic animals with early, moderate and late stages of heart failure was not different from the control values whereas the sodium fluoride- and catecholamine-stimulated adenylate cyclase activities were depressed in cardiomyopathic sarcolemma at moderate and late stages. 3. The sarcolemmal Na+ + K+-ATPase activity was decreased and the non-specific phosphatase activity was increased at early, moderate and late stages of heart failure. 4. The sarcolemmal Ca2+-ATPase activity was decreased at moderate and late stages whereas the Mg2+-ATPase activity was decreased at the late stages of heart failure only. 5. A marked decrease was found in calcium binding by heart sarcolemma from cardiomyopathic hamsters at late stages of failure. 6. These results suggest that dramatic sarcolemmal changes are associated with heart failure, and support the view that membrane abnormalities play a crucial role in the development of myocardial dysfunction, cyclase, calcium binding, heart failure, heart membranes, sarcolemmal enzymes.
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PMID:Comparison of heart sarcolemmal enzyme activities in normal and cardiomyopathic (UM-X7.1) hamsters. 13 61

A selective deficit in ouabain-sensitive adenosine triphosphatase has been shown in unilaterally obstructed dog kidneys; the deficit correlates inversely with Na+ and K+ excretion following relief of obstruction. It is postulated that the enzymatic defect may play a role in the etiology of postobstructive diuresis.
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PMID:Etiology of postobstructive diuresis: ouabain-sensitive adenosine triphosphatase deficit and elevated solute excretion in the postobstructed dog kidney. 13 77

Several distinct transport mechanisms responsible for sodium reabsorption by the rat kidney can be identified by studying the function of isolated perfused kidneys. Approximately one-half of the fractional sodium reabsorption by the isolated perfused rat kidney appears to depend on Na-K-adenosine triphosphatase (AT-Pase) and is inhibited by ouabain. About 10 to 20% is associated with the reabsorption of bicarbonate and is blocked by acetazolamide. This fraction of transported sodium is unaffected by ouabain and therefore does not involve Na-K-ATPase. Neither furosemide nor ethacrynic acid produce further inhibition of sodium reabsorption in a kidney already exposed to ouabain and acetazolamide. Most of the residual transport of sodium is inhibited by cooling the perfused kidney, suggesting that it is powered by metabolic rather than physical sources of energy.
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PMID:Multiple pumps for sodium reabsorption by the perfused kidney. 13 14

The relationship between altered transmembrane sodium movements and myocardial contractility was studied by opposing the action of the sodium pump with grayanotoxin I (GTX), an agent previously shown to increase resting sodium influx. GTX failed to affect Na+,K+-adenosine triphosphatase activity in vitro in concentrations as high as 0.1 mM. In electrically driven left atrial preparations of guinea-pig hearts, 1 mugM GTX produced a slight depolarization and appeared to decrease the upstroke velocity of the action potential, GTX (0.1-1 mugM) also produced a positive inotropic effect which developed over a 20-minute period. At higher concentrations, GTX produced arrhythmias. These effects of GTX were also observed in the presence of 10 mugM propranolol. Positive inotropic and arrhythmic effects of GTX were reversible after washout of the drug. These effects of GTX were also reversed by tetrodotoxin, an agent which has been shown to counteract the effect of GTX on sodium permeability. These data are consistent with a hypothesis that altered transmembrane sodium movement effects myocardial contractility.
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PMID:Effects of grayanotoxin I on cardiac Na + K + -adenosine triphosphatase activity, transmembrane potential and myocardial contractile force. 13 36


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