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)

The interaction of the dissociated catalytic subunit of adenosine 3',5'-cyclic monophosphate-dependent protein kinase (kinase A) and phosphatidylinositol metabolism has been studied in rat spleen lymphocyte membranes. As reported previously (Sarkadi et al., FEBS Lett. 152: 195-198, 1983) addition of kinase A increased by about twofold the phosphorylation of phosphatidylinositol in lymphocyte membranes at low ATP concentrations. However, we have found that this increase is an artifact of the assay conditions, and that the increase is a consequence of an inhibition of membrane adenosine triphosphatase activity by the protein kinase A. When lipid phosphorylation was measured under initial rate conditions, at high ATP concentrations, the increase was abolished. No effect of kinase A was observed on initial rates of the synthesis or hydrolysis of phosphatidylinositol phosphate. No phosphatidylinositol bisphosphate was produced in the membranes under any of the assay conditions used.
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PMID:Kinase A does not activate phosphatidylinositol phosphorylation in rat lymphocyte membranes. 378 31

In porcine areolar placental epithelia, the following enzymes were demonstrated by histochemical methods after 30, 58, 80, 100, and 110 d of pregnancy, respectively: beta-N-acetyl-hexosaminidase, beta-galactosidase, beta-glucuronidase, alpha-mannosidase, acid phosphatase, alkaline phosphatase, nonspecific esterases, cytochrome oxidase, 5-nucleotidase, leucine aminopeptidase, adenosine triphosphatase, diaphorases (NADH, NADPH), glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase (NAD, NADP), beta-hydroxybutyrate dehydrogenase, glycero-3-phosphate dehydrogenase, NAD-glycero-3-phosphate dehydrogenase, glutamate dehydrogenase (NAD, NADP), lactate dehydrogenase. The results show that the enzyme activities remained almost unchanged during the period of investigation. Of the dehydrogenases, the diaphorases as well as succinate and lactate dehydrogenase demonstrated generally an intensive activity within the epithelia. The activity of the other dehydrogenases was only low. The activity of unspecific esterase was very intensive within the uterine epithelia but remarkably low within chorionic epithelia. Contrarily, the reaction of adenosine triphosphatase was more intensive within chorionic than uterine epithelia. All investigated glucosidases reacted distinctly positive within chorionic epithelia, but only beta-N-acetyl-hexosaminidase and beta-galactosidase in uterine epithelia. The high activity of acid phosphatase, especially within the chorionic epithelium, seems to be connected with uteroferrin, an iron-binding protein. The histochemical results are discussed in context with the function of the areolae in histiotrophic nutrition and iron transport.
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PMID:[Enzyme-histochemical studies of the pig placenta. II. Histotopics of enzymes in the areolar placenta epithelium]. 392 41

1. The preparation of gram quantities of isolated epithelial-cell ;ghosts' from mucosal scrapings of rat small intestine is described. The method involves dispersing the tissue by gentle homogenization in 6% dextran in Krebs-Ringer phosphate, pH7.4, followed by filtration through nylon cloth and sedimentation by low-speed centrifuging. 2. The isolated epithelial-cell ;ghosts' contained all of the DNA, but only 52% of the protein and 53-57% of the RNA of the original homogenate. They contained most of the activity of the following enzymes found in the homogenate: aminopeptidase (71%); alkaline beta-glycerophosphatase (82%); invertase (92%); adenosine triphosphatase (93-116%); acid beta-glycerophosphatase (83%); nonspecific esterase (76%); succinate dehydrogenase (96%). Only small proportions of the total lactate-dehydrogenase (10%) and phosphoglucose-isomerase (2%) activities found in the homogenate were recovered in the isolated cell ;ghosts'. 3. The epithelial-cell ;ghost' preparation did not respire unless cofactors and substrates were added, and did not consume glucose or produce lactic acid from glucose. 4. The effect of varying the composition of the homogenization medium was studied. Concentrations of dextran (mol.wt. 15x10(4)) from 1 to 12%, solutions of dextrans (all at 6%) with mol.wt. varying between 3.6x10(4) and 2x10(6), and a solution of 8% polyethylene glycol (mol.wt. 4000) served equally well for the production of epithelial-cell ;ghosts'. Two of these solutions, however, 12% dextran (mol.wt.15x10(4)) and 6% dextran (mol.wt. 2x10(6)), were too viscous to allow the complete sedimentation of the cell ;ghosts' at low relative centrifugal forces. Omission of either Krebs-Ringer phosphate or dextran from the medium resulted in almost complete cell breakage during the homogenization. 5. The isolated cell ;ghosts' were used as a starting material for subcellular fractionation of rat intestinal mucosa by differential centrifugation. The distributions of protein and succinate-dehydrogenase activity among the fractions were compared with corresponding values in fractions isolated by differential centrifugation of mucosa homogenized in 0.3m-sucrose-5mm-EDTA, pH7.4. The method in which cell ;ghosts' were used as starting material gave a better separation and cleaner fractions than the method in which untreated mucosal scrapings were used.
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PMID:The isolation and properties of epithelial-cell "ghosts" from rat small intestine. 422 Sep 68

Peptides obtained from pepsin digestion of the phosphorylated and nonphosphorylated forms of a preparation of brain microsomal sodium-potassium-activated adenosine triphosphatase were treated at pH 5.4 with N-(n-propyl-2,3-(3)H) hydroxylamine of high specific activity, then separated by column chromatography, and further digested with pronase. A compound isolated in higher amounts from the phosphorylated enzyme than from the nonphosphorylated enzyme migrated with authentic L-glutamyl-gamma-propylhydroxamate in four chromatographic systems and on electrophoresis on paper at three different pH's. The acyl phosphate "intermediate" in the phosphorylated form of the adenosine-triphosphatase therefore appears to be an L-glutamyl-gamma-phosphate residue.
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PMID:Sodium-potassium adenosine triphosphatase: acyl phosphate "intermediate" shown to be L-glutamyl-gamma-phosphate. 422 45

1. Kidneys were kept anoxic at 4 degrees , 20 degrees and 38 degrees . Mitochondria were then isolated and their oxidative phosphorylation and respiration were determined. 2. Under all conditions the rate of phosphate esterification was affected to a greater extent, or earlier, than oxygen consumption. 3. Glutamate and succinate were used as substrates. The depression of P/O ratio was greater for glutamate at 4 degrees , and for succinate at 20 degrees . 4. Anoxia abolished the inhibiting effect of fluoride on respiration. 5. Phosphate esterification, after anoxia, was higher in the presence of fluoride than its absence, whereas in control preparations they were the same. 6. The decrease in P/O ratio did not appear to be due to activation of adenosine triphosphatase, as activities of both Mg(2+)-and dinitrophenol-activated adenosine triphosphatases were decreased after anoxia.
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PMID:The effect of temperature and anoxia of kidney on the subsequent oxidative phosphorylation of mitochondria. 422 26

Tritiated H(3)-digoxin specifically binds to a cardiac (Na(+) + K(+))-activated adenosine triphosphatase. In the presence of adenosine triphosphate and other nucleoside di- and triphosphates, binding is stimulated by sodium ion, the apparent rate constant being similar to that reported for phosphorus-32 incorporation from adenosine triphosphate and for the adenosine triphosphatase activity. In the presence of magnesium, manganese, inorganic phosphate, or other ions, sodium ion inhibits binding. The data support an allosteric type of sodium-potassium ion pump.
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PMID:Tritiated digoxin binding to (Na+ + K+)-activated adenosine triphosphatase: possible allosteric site. 423 May 10

An Mg(2+)-dependent and a K(+)-stimulated adenosine triphosphatase were localized by cytochemistry at or near both surfaces of the cytoplasmic membrane of Myxococcus xanthus. An alkaline and an acid phosphatase resided at the external surface of the membrane or in the periplasm. All enzymes could be extracted from partially fixed cells with Mg(2+)-deficient buffers. Suboptimal external phosphate elicited dissociation of adenosine triphosphatase from the membrane but not that of the unspecific phosphatases. The dissociated enzymes migrated into the cytoplasm where they were associated mainly with cytoplasmic aggregates.
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PMID:Cytochemistry of phosphatases in Myxococcus xanthus. 423 39

1. A study has been made of the cellular content and movement of Ca across the membrane of human red blood cells.2. The [Ca] in the cellular contents of fresh red cells is 4.09 x 10(-2) mM. The intracellular concentration of free ionic Ca ([Ca(2+)]) is considered to be less than this value and therefore less than extracellular [Ca(2+)] under normal conditions.3. Observation of unidirectional Ca fluxes with (45)Ca confirms previous reports of low permeability of the red cell membrane for Ca. After nearly 1 week of loading in the cold, intracellular (45)Ca content is 1.8% of extracellular (45)Ca content. Appearance in extracellular fluid of (45)Ca from coldloaded cells can be considered to arise from two compartments. Efflux of (45)Ca from the ;slower compartment' is accelerated by the addition of glucose.4. Starved red cells, incubated at 37 degrees C, after reversible haemolysis for loading with Ca and Mg-ATP, exhibit an outward net transport of Ca against an electrochemical gradient. The transport is associated with the appearance of inorganic phosphate (P(i)). Cells treated similarly, but without ATP show no transport and no appearance of P(i).5. During the initial phase of transport, 1.3 mole P(i) appear per mole Ca transported.6. The transport of Ca from ATP-loaded cells is highly temperature-dependent, with a Q(10) of 3.5.7. Cell membrane adenosine triphosphatase (ATPase) activity of reversibly haemolysed cells is stimulated only by intracellular, and not by extracellular Ca.8. Neither Ca transport in reversibly haemolysed cells, nor the Ca-Mg activated ATPase of isolated cell membranes is sensitive to Na, K, ouabain or oligomycin.9. Mg is not transported under the conditions which reveal Ca transport, but Mg appears to be necessary for Ca transport.10. Sr is transported from reversibly haemolysed Mg-ATP-loaded cells. Sr also can substitute for Ca, but not for Mg, in the activation of membrane ATPase.11. It is concluded that, in addition to a low passive permeability, an active extrusion mechanism for Ca exists in the human red cell membrane. This extrusion mechanism, in addition to a low passive membrane permeability for Ca, may represent the means by which intracellular Ca content is maintained at a low level. It is suggested that the Ca-Mg activated membrane ATPase and the active transport of Ca are two manifestations of the same process.
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PMID:Calcium movements across the membrane of human red cells. 423 81

A microsomal adenosine triphosphatase (ATPase) that requires both sodium and potassium ions is thought to be identical with, or an integral part of, the active cation transport system located in cell membranes. Attempts to isolate and purify (Na(+) + K(+))-ATPase have met with limited success because solubilization of microsomal protein causes partial, if not complete, loss of enzymatic activity. We now report the isolation from rat kidney microsomes of proteins which, though enzymatically inactive, could still be identified as components of the (Na(+) + K(+))-ATPase system. Phosphoproteins known to be intermediates in the hydrolysis of ATP by (Na(+) + K(+))-ATPase were prepared by incubating rat kidney microsomes with gamma-labeled ATP(33) in the presence of sodium or with P(32)-orthophosphate in the presence of ouabain. After the P(32)- and P(33)-labeled microsomes had been dissolved in phenol-acetic acid-urea, the resultant solutions were mixed and subjected to polyacrylamide gel electrophoresis. The radioactivity from both phosphorus isotopes was found almost exclusively in one of the resultant 21 protein bands. In contrast, the radioactive protein from DFP(32)-labeled microsomes moved slightly faster than the radioactive protein from microsomes labeled with P(33)-orthophosphate in the presence of ouabain. DFP inhibits (Na(+) + K(+))-ATPase by reacting with a nucleophilic site at or near the active site. These results suggest that while a single protein component of (Na(+) + K(+))-ATPase accepts the terminal phosphate from ATP, the final splitting of this phosphoprotein intermediate may be catalyzed by nucleophilic sites on a second protein.
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PMID:Identification of components of (Na+ plus K+)-adenosine triphosphatase by double isotopic labeling and electrophoresis. 424 29

When samples of pea tendril tissue were incubated in the Wachstein-Meisel medium for the demonstration of adenosine triphosphatases, deposits of lead reaction product were localized between the membranes of the chloroplast envelope. The presence of Mg(2+) was necessary for adenosine triphosphatase activity, and Ca(2+) could not substitute for this requirement. Varying the pH of incubation to 5.5 or 9.4 inhibited enzyme activity, as did the addition of p-chloromercuribenzoic acid or N-ethylmaleimide. The adenosine triphosphatase was apparently inactivated or degraded when the plants were grown in the dark for 24 hours prior to incubation. The enzyme was substrate-specific for adenosine triphosphate; no reaction was obtained with adenosine diphosphate, uridine triphosphate, inosine triphosphate, p-nitrophenyl phosphate, and sodium beta-glycerophosphate. Sites of nonspecific depositions of lead are described. The adenosine triphosphatase on the chloroplast envelope may be involved in the light-induced contraction of this organelle.
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PMID:Localization of adenosine triphosphatase activity on the chloroplast envelope in tendrils of Pisum sativum. 424 3


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