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)

Cardiac myosin obtained from atria had a higher Ca2+-activated ATPase activity than did cardiac myosin from ventricles in various species of animals and in humans. The increased specific activity of Ca2+-activated adenosine triphosphatase (ATPase) of atrial myosin appeared to correlate with the level of the activity of ventricular myosin ATPase in the animal, since the same order in ATPase activity, as observed in ventricular myosins from various animals, was noted in atrial myosins. The enzymatic properties of atrial myosin also were characterized by no activation by N-ethylmaleimide, low activating energy, and a lower rate of inactivation at alkaline pH compared with the same properties of ventricular myosin. These findings suggest a difference in the myosin molecule at or near the active site, involving some sulfhydryl groups, between the two types of cardiac myosin. The Mg2+-activated ATPase activity, both in the presence and absence of actin (which is thought to be closely related to the basic contraction mechanism), also was enhanced in atrial myosin. Thus, the ATPase activities of atrial and ventricular myosins were different with special reference to the reaction pathway involving calcium and magnesium ions and appear to account for the difference in the velocity of contraction between the atria and the ventricles.
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PMID:Cardiac atrial myosin adenosine triphosphatase of animals and humans: distinctive enzymatic properties compared with cardiac ventricular myosin. 3 14

This study examined the effects of vanadate on the potassium dependent phosphatase activity present in purified human kidney microsomal (Na+ + K+)-adenosine triphosphatase. Vanadate anion inhibited the K+-dependent phosphatase at a K1 of 35 nM. This inhibition was noncompetitive with the substrate, p-nitrophenylphosphate. The inhibition by vanadate at 1 mM K+ was only 45% of the inhibition that was observed at 10 mM K+. Neither preincubation of the enzyme with vanadate, nor changing the pH of the assay from 8.2 to 7.2 had any effect on the K1 for vanadate. The inclusion of 2.5 mM isoproterenol, to complex the yanadate, reversed the inhibition, as did diluting the enzymatic reaction. Vanadate also inhibited the overall (Na+ + K+)-ATPase reaction at a K1 of 1.91 microM. This inhibition was also reversible upon inclusion of isoproterenol in the assay. Increasing the level of magnesium from 6 mM to 30 mM lowered the K1 of vanadate to 0.25 microM. The possible role of vanadate as a physiological mediator of (Na+ + k+)-atpase activity is discussed.
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PMID:The effect of vanadate on human kidney potassium dependent phosphatase. 3 61

Growth of Clostridium perfringens was inhibited by compounds which dissipate or prevent the formation of electrochemical proton gradients. Membrane vesicles prepared from this organism exhibited Mg2+-dependent adenosine triphosphatase (ATPase) activity sensitive to N,N'-dicyclohexylcarbodiimide. Mg2+-ATPase activity was optimal of 50 degrees C, but no discrete pH optimum was observed. Adenosine triphosphate-dependent quenching of the fluorescence of the weak base quinacrine by everted membrane vesicles suggested that the Mg2+-ATPase is a proton pump capable of generating an electrochemical proton gradient. Adenosine triphosphate-dependent transport of Ca2+ by everted vesicles was sensitive to uncouplers and inhibitors of the Mg2+-ATPase.
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PMID:Properties and function of the proton-translocating adenosine triphosphatase of Clostridium perfringens. 4 Sep 63

The catecholamine transporter from bovine chromaffin granules has been solubilized by using low concentrations of sodium cholate in the presence of phospholipids. The functional solubilized protein has been incorporated into liposomes after removal of the detergent either by gel filtration or by dialysis. Reserpine-sensitive accumulation against a concentration gradient is achieved by artifically imposing a pH gradient across the membrane. In the reconstituted system adenosine 5'-triphosphate (ATP) serves as an energy source only at higher detergent concentrations. The proton-translocating adenosine triphosphatase (ATPase) is solubilized in parallel with the increasing efficiency of ATP as an energy source. Several criteria are proposed to distinguish between carrier-mediated (reserpine sensitive) and unmediated transport in the reconstituted system. The reserpine-sensitive process shows affinity and ss presented in this communication provide further support for the contention that concentrative uptake in biogenic amine storage vesicles is driven by a transmembrane pH gradient, which, in the native system, is generated by a proton-translocating ATPase. Moreover, the assays described provide a tool for the isolation and purification of the transport protein.
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PMID:Solubilization and reconstitution of the catecholamine transporter from bovine chromaffin granules. 4 69

Homogenates of Tritrichomonas foetus exhibited a Mg2+-dependent adenosine triphosphatase (ATPase) activity, with a pH optimum in Tris buffers of 8.2 to 8.3. The activity was not sensitive to oxygen. At high concentrations, quercetin and 4-chloro-7-nitrobenzofurazan inhibited ATPase activity in the cytoplasmic extract by 20 and 70%, respectively, whereas oligomycin, venturicidin, triethyltin, leucinostatin, dibutylchloromethyltin chloride, spegazzinine, efrapeptin, citreoviridin and sodium azide had no effect and N,N'-dicyclohexylcarbodi-imide stimulated the activity somewhat. The activity was localized in a population of small cytoplasmic particles which also contained an acid phosphatase. There was no indication of an association of ATPase with hydrogenosomes. The ATPase activity (or activities) in this aerotolerant anaerobe is different from the ATPases characteristic of mitochondria or of anaerobic bacteria.
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PMID:Adenosine triphosphatase activity of Tritrichomonas foetus. 4 53

The effect of ouabain, a specific sodium-potassium dependent adenosine triphosphatase (Na+-K+-ATPase) inhibitor, on antigen-induced histamine release was studied using guinea pig lung fragments sensitized in vitro with rabbit antibodies against bovine serum albumin. Histamine was assayed spectrofluorometrically. When sensitized tissue had been preincubated with ouabain (less than or equal to 1.0 x 10(-4) M) for 10 min prior to antigenic challenge, release of histamine was significantly inhibited (maximum 54%, p less than 0.001, N=9, paired t test). The most significant inhibition was obtained near the optimal concentration of antigen. The inhibition was dependent on the length of preincubation (less than or equal to 20 min), and was partially reversible upon washing the tissue removing the ouabain. Ouabain did not seem to prolong the duration of the histamine release process. Increase in potassium ion (less than or equal to 1.1 x 10(-2)M) inhibited the histamine release and had additive effects to ouabain action. Dibutyryl cyclic AMP (less than or equal to 5 x 10(-3) M), which could enhance the release, strongly antagonized the inhibition. Glucose removal from the medium did not abolish the ouabain effect. The results seem to indicate that immunologic release of histamine is under the influence of the membrane Na+-K+-ATPase activity.
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PMID:Inhibition of antigen-induced histamine release by ouabain. 5 30

The distribution of transport adenosine triphosphatase in the ferret placenta was examined cytochemically by light and electron microscopy. The enzyme was detected in the syncytiotrophoblast but was absent from maternal tissues. It appeared to be associated with cytoplasmic processses on syncytiotrophoblast surfaces directly related to foetal or maternal capillaries. The functional significance of transport adenosine triphosphatase is discussed with reference to the transport of solutes between the maternal and foetal circulation across the trophoblast layer.
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PMID:Cytochemical localization of transport adenosine triphosphatase in the ferret placenta. 6 Mar 6

The effects of fixation with various concentrations of glutaraldehyde or formaldehyde, acetone or ethanol, and freeze-drying on 5 phosphatases of Eimeria tenella and chick kidney cell cultures were demonstrated in situ. Gultaraldehyde inactivated the phosphatases more than did the formaldehyde, but the effect of the combination of the 2 (Karnovsky's fixative) was greater than that of either glutaraldehyde or formaldehyde alone. The higher the concentration of aldehyde and the longer the duration of exposure, the greater the inactivation. The order of sensitivity to aldehyde fixation of the enzymes tested was glucose-6-phosphatase greater than thiamine pyrophosphatase greater than 5'-nucleotidase greater than adenosine triphosphatase greater than acid phosphatase. Cytologic detail was preserved more efficiently with glutaraldehyde than with formaldehyde. Optimal preservation of enzyme activity for cytochemistry was with 2% glutaraldehyde for 30 min or 2% formaldehyde for 1 hr for G-6-Pase, TPPase, and 5'-nucleotidase, and with 2% glutaraldehyde or 2% formaldehyde for 2 hr with ATPase and AcPase. Quenching with subsequent fixation in cold acetone or ethanol resulted in complete inactivation of G-6-Pase, TPPase, and 5'-nucleotidase; although cells fixed in this manner yielded large amounts of reaction product for ATPase and AcPase, the distribution was diffuse, and some of it appeared to be artifactual. Quenching with subsequent freeze-drying was unsatisfactory because nearly all of the cell layers rolled off the cover glasses.
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PMID:Effect of fixation on demonstration of phosphatases of Eimeria tenella grown in chick kidney cell cultures. 6 Dec 71

The sodium-potassium activated adenosine triphosphatase (NaKATPase) activity of the rat cornea was investigated histochemically using a Pb2+-precipitation technique in which adenosine triphosphate (ATP) is used as substrate and two methods for potassium-dependent para-nitrophenyl-phosphatase (K-NPPase) activity. With all the three techniques used it was demonstrated that the sodium-potassium-activated adenosine triphosphatase (NaK-ATPase) activity is localized in the cell membranes of the endothelium whereas a much weaker activity was observed in the epithelium. When the Pb2+-technique was used, the epithelial cell membranes showed a weaker reaction in the presence of ouabain. This activity was only Mg2+-dependent and was presumably due to an Mg2+-dependent ATPase. The validity of the histochemical techniques for NaK-ATPase activity is discussed. The results emphasize the importance of the endothelium as the main site of Na+ transport in the cornea. Small amounts of the enzyme are also present in the epithelium, which seems to be rich in Mg2+-ATPase. Provided that careful controls are performed, all the methods give consistent results in the cornea.
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PMID:Transport adenosine triphosphatase activity in the rat cornea. 6 3

Three new techniques are described for staining the Langerhans cell in whole mounts of fresh human and guinea pig epidermis. These employ paraphenylenediamine, gold sodium thiomalate and cobalt chloride, respectively, and require appropriate epidermal separation with EDTA, ammonium thiocyanate or sodium bromide. Used in conjunction with a modified adenosine triphosphatase stain, these techniques provide greater capability for observing the Langerhans cell in disease states than can be achieved by any single stain. A combined stain with adenosine triphosphate and gold is also described.
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PMID:New staining techniques for the Langerhans cell. 7 Sep 19


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