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)

Phosphoinositide content was measured in erythrocyte membranes from 11 patients with cystic fibrosis (CF) and from 12 control subjects to determine whether altered levels of phosphatidylinositol-4-phosphate (Ptdlns4P) or phosphatidylinositol-4,5-bisphosphate (Ptdlns(4,5)P2) are responsible for the decrease in Ca2+-adenosine triphosphatase (Ca2+-ATPase) activity in this disorder. Isolated membranes were extracted with an acidified chloroform-methanol solvent system. The recovered lipids were separated by one-dimensional thin-layer chromatography and quantified with a colorimetric assay for phosphorus. The results are expressed in molar percent, moles of phosphoinositide times 100 divided by the total number of moles of phospholipid per membrane. The means +/- SEM of Ptdlns(4,5)P2, Ptdlns4P, and phosphatidylinositol (Ptdlns) in CF membranes (1.07 +/- 0.18, 1.02 +/- 0.22, and 2.32 +/- 0.36 molar percent, respectively) were indistinguishable from controls (0.91 +/- 0.14, 0.85 +/- 0.12, and 2.21 +/- 0.32 molar percent, respectively) (P greater than 0.20 for all three pairs). The accuracy of quantitative recovery throughout the procedure was determined by adding a radioactive internal standard, L-3-phosphatidyl[2-3H]inositol to 10 membrane preparations. Although quantitative recoveries, as determined by percent radioactivity recovered, varied from 54% to 92%, mean Ptdlns(4,5)P2, Ptdlns4P, and Ptdlns levels appropriately corrected from tracer loss were still indistinguishable between the two groups. We conclude that absolute phosphoinositide levels are not altered in cystic fibrosis erythrocyte membranes and that the differences in Ca2+-ATPase activity cannot be explained on this basis.
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PMID:Phosphoinositide content of erythrocyte membranes in cystic fibrosis. 283 Mar 55

Of all tissues of the extremities, muscle is the least tolerant of ischemia. Hypothermia of tissue is considered beneficial for the maintenance of viability of muscle in amputated limbs before surgical replantation, but it has never been established that conventional cooling in an ice bath or its equivalent (temperature of tissue, approximately 1 degree Celsius) is the optimum level of hypothermia for minimizing metabolic derangement in ischemic muscle. In this study, we first defined the time course and level of metabolic derangement of muscle in twenty-eight ischemic hind limbs in cats at 22, 15, 10, 5, and 1 degree Celsius. The levels of adenosine triphosphate and phosphocreatine and the mean intracellular pH of the muscles in the lateral aspect of the thigh in each limb were monitored with phosphorus nuclear magnetic-resonance spectroscopy over time. The excised muscles from six freshly amputated legs of live humans were then similarly studied to determine whether muscles from cats and from humans exhibit comparable bioenergetic responses to hypothermic ischemia. A final series of ten ischemic hind limbs from cats was studied by nuclear magnetic resonance and muscle biopsy for direct biochemical assay of tissue energy metabolites to compare the metabolic benefits of two different methods of preserving limbs: continuous cooling in an ice bath, and a newly devised protocol for the rapid induction and maintenance of so-called intermediate (10 +/- 5 degrees Celsius) hypothermia of tissue. Ischemic skeletal muscle in cats exhibited a paradoxical metabolic response to extreme cold (1 degree Celsius). The rate of metabolic deterioration progressively declined with decreasing temperature of tissue to 10 degrees Celsius. However, at 5 degrees Celsius, no additional benefit was detected, and at 1 degree Celsius, there was a significant acceleration in the rates of degradation of adenosine triphosphate and phosphocreatine and in the production of lactate. The rate of degradation of adenosine triphosphate in human ischemic muscle was also faster at 1 degree Celsius than at 10 degrees Celsius. This paradoxical response is apparently due to a severe inhibition of the calcium pump of the sarcoplasmic reticulum of the muscle cell at temperatures of less than 5 degrees Celsius. The inhibition permits an efflux of calcium to the myofibrils, which stimulates both glycolysis and the degradation of adenosine triphosphate by myofibrillar adenosine triphosphatase.
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PMID:The bioenergetics of preservation of limbs before replantation. The rationale for intermediate hypothermia. 319 76

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

The preparation of cytoplasmic membranes from suspensions of Staphylococcus aureus lysed by an enzyme recently isolated in these laboratories is described. These membranes contained: protein, 34.4%; ribonucleic acid, 6.6%; lipids, 34.5%; and total phosphorus, 1.4%. Such membranes exhibited adenosine 5'-triphosphatase (E.C. 3.6.1.3) activity, liberating orthophosphate at an initial rate of 0.53 mumole per min per mg of protein under optimal conditions. The enzyme was Mg(++)-dependent and K(+)- or Na(+)-stimulated. Maximal activity was observed with a molar adenosine 5'-triphosphate (ATP) to Mg(++) ratio of 1. One mole of orthophosphate was liberated per mole of ATP; the other product of digestion was adenosine 5'-diphosphate. Inorganic pyrophosphate and the 5'-triphosphates of guanosine, uridine, and cytidine were also attacked by membrane preparations, but more slowly than ATP. Ouabain, p-chloromercuribenzoate, and 2,4-dinitrophenol did not alter adenosine triphosphatase activity, whereas both Atebrine and chlorpromazine were inhibitory.
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PMID:Adenosine triphosphatase in isolated membranes of Staphylococcus aureus. 423 Aug 57

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

Protoplasts of Listeria monocytogenes strain 42 were fractionated after control lysis on a Ficoll (a polysucrose) density gradient. Visually, five zones could be recognized in the gradient. The first one was composed of amorphous cytoplasmic solutes (fraction 1a) and a mixture of particles (fraction 1b). These were: (i) light particles that were lipase-sensitive and composed of six subunits and (ii) heavy particles, sensitive to ribonuclease and devoid of fine structure. The second zone consisted of tubules and vesicles still harboring cytoplasmic components (fraction 2), whereas the third zone contained only empty vesicles and protoplast ghosts (fraction 3). The material congregating into the fourth zone was morphologically identical to that of the third (fraction 3a). The fifth and heaviest zone contained a mixture of (i) particles without any substructure and (ii) partly lysed protoplasts (fraction 4). Fractions 1b and 4 were the richest in nucleic acids (ribonucleic acid, 11.4 and 9.4%, respectively; deoxyribonucleic acid, 5.1 and 4.8%, respectively), whereas fraction 1b had the highest protein contents (74.6%). Phospholipids were mainly found in fractions 2 and 3. Except for fraction 1, all materials contained significant amounts of protein-bound phosphorus. The main concentrations of four enzymes were: glucose-6-phosphate dehydrogenase (fraction 1a); adenosine triphosphatase and reduced nicotinamide adenine diphosphate oxidase (fraction 3); nitro blue tetrazolium chloride reductase (fraction 2). Fractionation of strain 42 after addition of (32)P during the mid-log phase of growth revealed that the radio-activity was mainly detected in fraction 1b, when growth in the presence of the marker was allowed for 10 min, and in fraction 2, when growth was allowed for 90 min. The vesicles of fraction 2, often tubular, are probably of mesosomal origin, whereas those of fraction 3, which are always spherical, represent, most likely, the bulk of the cell plasma membrane. Our data showed slight chemical differences between these two fractions, but the differences in enzymatic activities and lipid-phosphorus incorporation during long pulse experiments were most dramatic.
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PMID:Fractionation and characterization of the plasma and mesosome membrane of Listeria monocytogenes. 430 41

The renal actions of differing doses of sodium orthovanadate were studied in conscious and anesthetized female Wistar rats. In conscious rats, sodium orthovanadate was given by i.v. or i.p. injections or by mouth. The most pronounced renal effects were seen after a 5 mg/kg i.p. injection of sodium orthovanadate. Urine flow and sodium excretion increased approximately 400% and urine osmolality fell from 1108 to 549 mOsmol/kg . H2O. Higher doses of sodium orthovanadate (20, 30 and 50 mg/kg) injected i.p. did not cause diuresis and were toxic. In anesthetized rats undergoing a 0.9% NaCl diuresis, i.v. infusion of sodium orthovanadate at a dose of 5 mg/kg/hr significantly increased urine flow and the excretion of sodium, calcium, phosphorus, sulfur, magnesium and chlorine, whereas glomerular filtration rate was unaltered. In anesthetized rats undergoing a water diuresis, i.v. infusion of sodium orthovanadate (5 mg/kg/hr) markedly reduced free-water clearance, indicating that this compound inhibits tubular reabsorption of sodium and chloride in diluting nephron segments. Blood and renal tissue levels of vanadium, measured using emission spectrographic analysis, in rats infused with sodium orthovanadate were 4 times higher than the concentration of sodium orthovanadate (1--10 microM) needed to inhibit 50% of the Na-K-adenosine triphosphate activity of rat renal homogenates in vitro. These data suggest that sodium orthovanadate produces diuresis at least in part by inhibiting Na-K-adenosine triphosphatase and solute transport in the distal nephron, likely the ascending limb of the loop of Henle.
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PMID:Sodium orthovanadate diuresis in rats. 626 66

Phosphatase activity in Trypanosoma rhodesiense has been examined histochemically by light and electron microscopy and by enzymatic assay in homogenate fractions. Using a method with lead as capture ion, acid phosphatase was found in lysosome-like vesicles and in the flagellar pocket. No alkaline adenosine triphosphatase (ATPase) was detectable by this method. Direct assay of p-nitrophenylphosphatase activity in homogenate fractions showed that acid phosphatase activity was strongly membrane-bound, but that activity at pH 9 was minimal in both soluble and particulate fractions. "Endogenous" ATPase activity was localized specifically and reproducibly in the mitochondrial membranes and under the plasma membrane of he flagellum. This nonenzymic reaction product could not be eradicated by glycerol extraction or glucose depletion. Unlike the membrane staining, which was manifest only after lead treatment, heat-resistant electron-dense material was found in the matrix of lysosomal vesicles in trypanosomes fixed in glutaraldehyde only and not subjected to further treatment with heavy metal reagents. X-ray emission analysis showed the presence of calcium and phosphorus, indicating that the matrix might have a phosphate storage function.
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PMID:Localization of phosphatases in Trypanosoma rhodesiense. 645 52

Phosphorus-31 nuclear magnetic resonance (31P-NMR) analysis was performed on normal (line 412) and dystrophic (line 413) superficial pectoralis muscles excised from chickens between 15 and 116 days after hatching. An apparent alteration in dystrophic muscle energy metabolism was abolished by pretreatment with curare and was attributed to muscle hyperexcitability. Time-dependent 31P-NMR studies demonstrated no apparent difference in the overall tissue adenosine triphosphatase (ATPase) activity of dystrophic as compared to normal muscle. After 55 days of age, a resonance signal attributed to serine ethanolamine phosphodiester (SEPDE) was observed only in dystrophic muscle. Adding the paramagnetic cation Mn2+ to the buffer surrounding the muscle resulted in an approximate 80% decrement in the dystrophic SEPDE signal without apparent alteration of the other phosphatic signals in either the normal or dystrophic muscle. This would argue against any generalized membrane defect in dystrophic chicken muscle and suggest that SEPDE is in a compartment accessible to Mn2+.
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PMID:31P-NMR studies of normal and dystrophic chicken muscle. 654 98

Muscle biopsy specimens form 22 patients with primary hypertension, 10 patients with chronic renal failure and 21 healthy normotensive controls were analyzed using a Kevex 0600 X-ray spectrometer. Muscle potassium (MK), calcium (MCa), sulphur (MS) and phosphorus (MP) were determined. In the patients with primary hypertension, MK was decreased compared to the controls (p less than 0.001), MCa was increased (p less than 0.05), MS was decreased (p less than 0.05) and no difference was seen in MP. In the patients with chronic renal failure, MK was decreased compared to the controls (p less than 0.001), MCa showed no difference compared to the controls, whereas both MP and MS were lower (p less than 0.05 and p less than 0.001). It was concluded that intracellular potassium is low both in primary hypertension and chronic renal failure. In chronic renal failure the potassium decrease is probably secondary to loss of cellular potassium capacity, whereas in primary hypertension an inhibition of the sodium, potassium, adenosine triphosphatase is suggested as the cause of the low potassium.
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PMID:Potassium in skeletal muscle in untreated primary hypertension and in chronic renal failure, studied by X-ray fluorescence technique. 673 Oct 36


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