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)

Red cells of newborn calves contain 105-110 mmole K(+) and 1-5 mmole Na(+) per liter of cells. As the animals age the K(+) content decreases to a value of 25-30 mmole/liter of cells after about 60 days. At approximately the same time, the sodium content reaches a value of 60-70 mmole/liter. The time required for half change (t((1/2))) is 35-37 days for both Na(+) and K(+). The activity of (Na + K)-adenosine triphosphatase (ATPase) and the influx of K(42) and Rb(86) into the red cells are high at birth and are reduced to 5 and 15% of their original values, respectively, in mature animals. t((1/2)) for both is of the order of 30-35 days. The membrane Mg-ATPase activity is also high at birth and is reduced with a t((1/2)) of 28-32 days to a final value of about 20% of its activity at birth. Separation of red cells according to their age showed that, in animals at the age of transition, newly formed red cells contain a higher K/Na ratio and a higher active transport capacity than older red cells of the same animal. It is suggested that the changes observed are a reflection of the average age of the red cell population as the animal grows.
J Gen Physiol 1972 Mar
PMID:Changes from high potassium (hk) to low potassium (lk) in bovine red cells. 425 45

Purified actin does not stimulate the adenosine triphosphatase (ATPase) activity of Limulus myosin greatly. The ATPase activity of such reconstituted preparations is only about one-fourth the ATPase of myofibrils or of natural actomyosin. Actin preparations containing tropomyosin, however, activate Limulus myosin fully. Both the tropomyosin and the actin preparations appear to be pure when tested by different techniques. Tropomyosin combines with actin but not with myosin and full activation is reached at a tropomyosin-to-actin ratio likely to be present in muscle. Tropomyosin and actin of several different animals stimulate the ATPase of Limulus myosin. Tropomyosin, however, is not required for the ATPases of scallop and rabbit myosin which are fully activated by pure actin alone. Evidence is presented that Limulus myosin, in the presence of ATP at low ionic strength, has a higher affinity for actin modified by tropomyosin than for pure actin.
J Gen Physiol 1972 Apr
PMID:Activation of the adenosine triphosphatase of Limulus polyphemus actomyosin by tropomyosin. 426 Apr 94

The relationship between active extrusion of Ca(++) from red cell ghosts and active uptake of Ca(++) by isolated red cell membrane fragments was investigated by studying the Ca(++) uptake activities of inside-out and right side-out vesicles. Preparations A and B which had mainly inside-out and right side-out vesicles, respectively, were isolated from red cell membranes and were compared with respect to Ca(++) adenosine triphosphatase (ATPase) and ATP-dependent Ca(++) uptake activities. Preparation A had nearly eight times more inside-out vesicles and took up eight times more (45)Ca in the presence of ATP compared to preparation B. Separation of the (45)Ca-labeled membrane vesicles by density gradient centrifugation showed that the (45)Ca label was localized to the inside-out vesicle fraction. In addition, the (45)Ca taken up in the presence of ATP was lost during a subsequent incubation in the absence of ATP. The rate of (45)Ca loss was not influenced by the presence of EGTA, but was slowed in the presence of La(+8) (0.1 mM) in the efflux medium. The results presented here support the thesis that the active uptake of Ca(++) by red cell membrane fragments is due to the active transport of Ca(++) into inside-out vesicles.
J Gen Physiol 1972 Apr
PMID:Active calcium ion uptake by inside-out and right side-out vesicles of red blood cell membranes. 426 Apr 95

The electrophysiological properties of embryonic chick hearts (ventricles) change during development; the largest changes occur between days 2 and 8. Resting potential (E(m)) and peak overshoot potential (+E(max)) increase, respectively, from -35 mv and +11 mv at day 2 to -70 mv and +28 mv at days 12-21. Action potential duration does not change significantly. Maximum rate of rise of the action potential (+V(max)) increases from about 20 v/sec at days 2-3 to 150 v/sec at days 18-21; + V(max) of young cells is not greatly increased by applied hyperpolarizing current pulses. In resting E(m) vs. log [K(+)](o) curves, the slope at high K(+) is lower in young hearts (e.g. 30 mv/decade) than the 50-60 mv/decade obtained in old hearts, but the extrapolated [K(+)](i) values (125-140 mM) are almost as high. Input resistance is much higher in young hearts (13 M ohm at day 2 vs. 4.5 M ohm at days 8-21), suggesting that the membrane resistivity (R(m)) is higher. The ratio of permeabilities, P(Na)/P(K), is high (about 0.2) in young hearts, due to a low P(K), and decreases during ontogeny (to about 0.05). The low K(+) conductance (g(K)) in young hearts accounts for the greater incidence of hyperpolarizing afterpotentials and pacemaker potentials, the lower sensitivity (with respect to loss of excitability) to elevation of [K(+)](o), and the higher chronaxie. Acetylcholine does not increase g(K) of young or old ventricular cells. The increase in (Na(+), K(+))-adenosine triphosphatase (ATPase) activity during development tends to compensate for the increase in g(K). +E(max) and + V(max) are dependent on [Na(+)](o) in both young and old hearts. However, the Na(+) channels in young hearts (2-4 days) are slow, tetrodotoxin (TTX)-insensitive, and activated-inactivated at lower E(m). In contrast, the Na(+) channels of cells in older hearts (> 8 days) are fast and TTX-sensitive, but they revert back to slow channels when placed in culture.
J Gen Physiol 1972 Oct
PMID:Changes in membrane properties of chick embryonic hearts during development. 426 8

The rate coefficient for (22)Na release from previously labeled human erythrocytes was determined in the presence of 0.1-10 mM sodium fluoride (F). The oxidized nicotinamide adenine dinucleotide (NAD(+)) level at the end of 2 hr of incubation in tris(hydroxymethyl)aminomethane (Tris)-Ringer medium was also measured. Both parameters decreased proportionately as F concentration was raised. Both F-induced changes were immediate and were reversed by 10 mM pyruvate. The decrease in NAD(+) concentration following enolase inhibition by F is attributed to a diminished rate of formation in the reaction catalyzed by lactic dehydrogenase (LDH) with undiminished continued utilization in the reaction catalyzed by glyceraldehyde-3-phosphate dehydrogenase (GAPDH). It is postulated that the NAD(+) lowering limited the GAPDH step, resulting in proportionate decreases in the rates of phosphoglycerate kinase (PGK) and Na,K-dependent adenosine triphosphatase (Na,K-ATPase), a reaction sequence thought to link glycolysis with active Na extrusion. Adding pyruvate with F increased NAD(+) production at the LDH step, thus reactivating GAPDH, PGK, and Na,K-ATPase and leading to the observed restoration of (22)Na release. The results suggest, therefore, that F inhibits active Na transport in intact human erythrocytes indirectly through a lowering of NAD(+), although, direct inhibition of the Na,K-ATPase by F may possibly occur simultaneously.
J Gen Physiol 1972 Sep
PMID:The role of oxidized nicotinamide adenine dinucleotide in fluoride inhibition of active sodium transport in human erythrocytes. 434 51

Red blood cell Na+, K+-, Mg2+-, and Ca2+-adenosine triphosphatase (ATPase) activities were studied longitudinally in eight patients with affective disorders and 12 healthy volunteers. The patients had a higher mean Ca2+-ATPase activity than the volunteers, and the fluctuations in all three ATPase activities were greater in the patients than in the volunteers. Even though the mean Ca2+-ATPase activity was higher during manias and euthymic periods than during depressions, mood and ATPase activities did not correlate with each other in all patients. Lithium carbonate treatment did not alter the ATPase activities, and the quantity of vanadium present in the membranes could not account for the variations in the enzyme activities observed. We suggest that either the RBCs of manic-depressive patients are very sensitive to fluctuations of a lipophilic ATPase activity--regulating factor present in plasma or the patients have at times high levels of such a factor. In some patients, the level of this hypothesized regulator may fluctuate in synchrony with mood changes.
Arch Gen Psychiatry 1983 Sep
PMID:RBC membrane adenosine triphosphatase activities in patients with major affective disorders. 613 2

A procedure has been developed for the large-scale fractionation into size and age classes of bacteria from exponentially growing cultures of Escherichia coli K12 by centrifugation through an equivolumetric gradient of sucrose in a zonal rotor. The resolution attained is superior to that in methods of this type that have been described previously. The activity of adenosine triphosphatase (ATPase) was assayed in extracts from bacteria separated into size classes by this method and from synchronous cultures prepared by size selection. Activity approximately doubled during a cell cycle, but the experimental data did not fit models of either continuously or exponentially increasing activity during the cycle. It is suggested that ATPase activity oscillates during the cell cycle with maxima at about 0.37 and 0.80 of a cycle. The fluctuations in activity greatly exceed the variations due to experimental error and, in the case of synchronous cultures, do not arise from perturbations in growth behaviour following zonal gradient selection. Sensitivity of ATPase activity to 75 micrometer-Ruthenium Red also fluctuates during the cell cycle, with maximum inhibition (60 to 80%) occurring near the middle of the cycle, a time that does not coincide with maximum enzyme activity.
J Gen Microbiol 1980 Sep
PMID:Adenosine triphosphatase activity and its sensitivity to ruthenium red oscillate during the cell cycle of Escherichia coli K12. 616 39

The sensitivity of RBC membrane (RBCM) Ca2+-adenosine triphosphatase (Ca2+-ATPase) to calmodulin stimulation was repeatedly studied in healthy volunteers and in 12 patients with affective disorders. Whereas control response was relatively stable, the patients showed great variability. This phenomenon was not due to formation of resealed vesicles in the RBCM nor to the quantity of calmodulin remaining in the RBCM preparations present in the cells before hemolysis. Changes in calmodulin sensitivity did not correlate with changes of mood or of drug treatment. When Ca2+-ATPase was relatively unresponsive to calmodulin, considerable enzyme activity was maintained at low calcium concentrations without calmodulin. In samples showing a large response to calmodulin, virtually no enzyme activity was detected at low calcium concentrations without exogenous calmodulin. Thus, calcium dependence and calmodulin sensitivity of the Ca2+-ATPase appeared to correlate positively with each other. As a similar phenomenon has been linked to changes in the composition of membrane phospholipids responsible for the regulation of Ca2+-ATPase activity, variations in baseline activity and calmodulin-induced stimulation of this enzyme may represent a fundamental defect in systems regulating membrane phospholipid composition.
Arch Gen Psychiatry 1984 May
PMID:Sensitivity of RBC membrane Ca2+-adenosine triphosphatase to calmodulin stimulation. Variations in patients with bipolar affective disorders. 623 7

Mitochondrial adenosine triphosphatase (ATPase) of the ciliate protozoon Tetrahymena pyriformis ST is completely inhibited by antiserum prepared against F1-ATPase purified from Schizosaccharomyces pombe, and by naturally occurring inhibitor proteins from this yeast and from bovine heart mitochondria. An ATPase inhibitor protein is also present in extracts of T. pyriformis. Mitochondrial ATPase of T. pyriformis is only partially inhibited by the F0-ATPase inhibitors N,N'-dicyclohexylcarbodiimide, oligomycin, leucinostatin, triethyltin sulphate and venturicidin, and (at high titres) by the F1-ATPase inhibitors Dio-9, efrapeptin, 4-chloro-7-nitrobenzofurazan and spegazzinine. Aurovertin, citreoviridin and quercetin were not inhibitory. Resistance to inhibitors distinguishes this mitochondrial ATPase from all those previously examined.
J Gen Microbiol 1981 Oct
PMID:Effects of inhibitors on mitochondrial adenosine triphosphatase of Tetrahymena pyriformis ST. 646 27

Sodium and potassium ion transport adenosine triphosphatase accepts and donates a phosphate group in the course of its reaction sequence. The phosphorylated enzyme has two principal reactive states, E1P and E2P. E1P is formed reversibly from ATP in the presence of Na+ and is precursor to E2P, which equilibrates with P(i) in the presence of K+. We studied equilibrium between these states at 4 degrees C and the effect of Na+ on it. To optimize the reaction system we used a Hofmeister effect, replacing the usual anion, chloride, with a chaotropic anion, usually nitrate. We phosphorylated enzyme from canine kidney with [32P]ATP. We estimated interconversion rate constants for the reaction E1P <--> E2P and their ratio. To estimate rate constants we terminated phosphorylation and observed decay kinetics. We observed E1P or E2P selectively by adding K+ or ADP respectively. K+ dephosphorylates E2P leaving E1P as observable species; ADP dephosphorylates E1P leaving E2P as observable species. We fitted a 2-pool model comprising two reactive species or a twin 2-pool model, comprising a pair of independent 2-pool models, to the data and obtained interconversion and hydrolysis rate constants for each state. Replacing Na+ with Tris+ or lysine+ did not change the ratio of interconversion rate constants between E1P and E2P. Thus Na+ binds about equally strongly to E1P and E2P. This conclusion is consistent with a model of Pedemonte (1988. J. Theor. Biol. 134:165-182.). We found that Na+ affected another equilibrium, that of transphosphorylation between ATP x dephosphoenzyme and ADP x E1P. We used the reactions and model of Pickart and Jencks (1982. J. Biol. Chem. 257:5319-5322.) to generate and fit data. Decreasing the concentration of Na+ 10-fold shifted the equilibrium constant 10-fold favoring ADP x E1P over ATP x dephosphoenzyme. Thus Na+ can dissociate from E1P x Na3. Furthermore, we found two characteristics of Hofmeister effects on this enzyme.
J Gen Physiol 1997 May
PMID:Equilibrium of phosphointermediates of sodium and potassium ion transport adenosine triphosphatase: action of sodium ion and Hofmeister effect. 915 1


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