Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The terminal phosphate of (gamma-32P)ATP is rapidly incorporated into cardiac sarcoplasmic reticulum membranes (0.7--1.3 mumol/g protein) in the presence of calcium and magnesium. Cardiac sarcoplasmic reticulum membranes catalize an ATP-ADP phosphate exchange in the presence of calcium and magnesium. 2. Half-maximum activation of the phosphoprotein formation and ATP-ADP phosphate exchange is reached at an ionized calcium concentration of about 0.3 muM. The Hill coefficients are 1.3. 3. Transphosphorylation and ATP-ADP phosphate exchange require magnesium and are maximally activated at magnesium concentrations close to or equal to the ATP concentration. 4. The phosphoprotein level is reduced to about 45% at an ADP/ATP ratio of 0.1. The rate of calcium-dependent ATP splitting declines, whilst the rate of the calcium-dependent ATP-ADP phosphate exchange increases when the ADP/ATP ratio is varied from 0.1 to 1. The sum of both, the rate of ATP splitting and the rate of ADP-ATP phosphate exchange remains constant. 5. Phosphoprotein formation and ATP-ADP phosphate exchange are not affected by azide, dinitrophenol, dicyclohexyl carbodiimide and oubain, whilst both activities are reduced by blockade of -SH groups localized on the outside of the sarcoplasmic reticulum membrane. 6. The isolated phosphoprotein is acid stable. The trichloroacetic acid denatured 32P-labelled membrane complex is dephosphorylated by hydroxylamine, which might indicate that the phosphorylated protein is an acyl-phosphate. 7. Polyacrylamide gel elctrophoresis (performed with phenol/acetic acid/water) of phosphorylated sarcoplasmic reticulum fractions demonstrates that the 32P-incorporation occurs into a protein of about 100000 molecular weight. 8. It is suggested that the phosphoprotein represents a phosphorylated intermediate of the calcium-dependent ATPase which formation occurs as an early step in the reaction sequence of calcium translocation by cardiac sarcoplasmic reticulum similar as in skeletal muscle.
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PMID:Characterization of cardiac sarcoplasmic reticulum ATP-ADP phosphate exchange and phosphorylation of the calcium transport adenosine triphosphatase. 0 67

The properties of a (Na+ plus K+)-dependent ATPase (ATP phosphohydrolase, EC 3.6.1.3) activator contained in leukocytic extracts was investigated. Intact polymorphonuclear leukocytes release the activator in a time- and temperature-dependent process. It is non-dialyzable through cellophane; inactivated by protease, trypsin, or phenol; contains essential sulfhydryl groups; and is heat and acid labile. Treatment of ATPase with the activator and subsequent removable of the activator from mixtures did not reverse the ATPase activation.
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PMID:Activation of rabbit brain microsomal (Na+ plus K+)-dependent ATPase by a leukocytic product. 12 98

Previous studies showed that microsomal (Na+ + K+)ATPase (ATP phosphohydrolase, EC 3.6.1.3) is activated by a proteinaeous material released by polymorphonuclear leukocytes. Investigations on the mode of action of the activator have been conducted by the siolation of 32P-labeled phosphoenzyme intermediates formed in the reaction of ATP and (Na+ + K)-ATPase, which has been postulated to occur through the formation and hydrolysis of acyl phosphate intermediates. The activator caused a concentration-dependent decrease in the recovery of phosphoenzyme intermediates that was not quantitatively altered by the Na+ or K+ concentration of the reaction mixture of by the presence of 1 mM oubain. A decline in phosphoenzyme intermediate recovery was promoted by the addition of the activator to preformed phosphoenzyme intermediates but not by activator that had been pretreated with protease or phenol. In addition, the activator caused a concentration-dependent stimulation of the p-nitrophenyl phosphatase and acetyl phosphatase activities of microsomal (Na+ + K+)-ATPase. It was proposed that the activator stimulates the dephosphorylation step of the (Na+ + K+)-ATPase reaction sequence.
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PMID:Further studies on the activation of microsomal (Na+ + k+)-atpase by a leukocytic product. 17 92

The release of lipoteichoic acid and mesosomal vesicles to the supernatant buffer during the formation of spherical, osmotically fragile bodies was studied using Streptococcus faecalis ATCC 9790. Autolytic N-acetylmuramidase action was permitted to take place in exponential-phase cells incubated in a buffer which provides an exceptional degree of osmotic stabilization. Both lipoteichoic acid and mesosomal vesicles were relatively rapidly released to the supernatant buffer. Most of the cellular content of lipoteichoic acid (and mesosomal vesicles) was found in the supernatant buffer at incubation times when the cells still retained over 75% of their cell wall. [14-C]- or [3-H]glycerol was used as a label for both cellular lipoteichoic acids and lipid-glycerol. Glycerol in lipoteichoic acid was quantitated after phenol-water and chloroform-methanol treatments and identified by products of acid hydrolysis and its ability to be precipitated by (i) antibodies specific for the polyglycerol-phosphate backbone, (ii) antibodies to the streptococcal group D antigen, and (iii) concanavalin A. Evidence was obtained that lipoteichoic acid was not associated with isolated mesosomal vesicles. Centrifugation of supernates at 200,000 X g sedimented membranous (mesosomal) vesicles and nearly all of the lipid-glycerol present, whereas essentially all of the lipoteichoic acid remained in the supernatant. The sedimented mesosomal vesicles differed from protoplast membrane in their higher lipid-phosphorus to protein ratio and in the absence of detectable levels of two enzymatic activities found in protoplast membranes, adenosine triphosphatase and polynucleotide phosphorylase. Both types of membranes were found to contain DD-carboxypeptidase and LD-transpeptidase activities at nearly the same specific activities. No evidence was obtained for the association of autolytic N-acetylmuramidase activity with either type of membrane preparation.
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PMID:Cellular localization of lipoteichoic acid in Streptococcus faecalis. 80 56

Tubular basement membrane (BM) changes (dysmorphogenesis), cell proliferation, and fluid accumulation related to the altered location of Na,K-ATPase are purported essential key events in the development and progression of renal cysts. These changes were assessed daily in Phenol II (2-amino-4-hydroxyphenyl-5-phenyl thiazole)-treated rats, which rapidly develop marked and progressive cystic change of all collecting tubules (CT). At Day 1, 12% of CT were cystic and their BM were thickened severalfold. At Day 4, 30% of CT were cystic and their BM remained thickened. BM of cystic tubules showed decreased staining for heparan sulfate proteoglycan and increased staining for fibronectin. Proliferation, as determined by (3H)thymidine, incorporation, was not significant until Day 2 and involved cystic and noncystic tubular cells as well as interstitial cells. As cystic changes progressed, cell proliferation decreased. By immunohistochemistry, the altered location of Na,K-ATPase in epithelial cells lining cysts was primarily detected after Day 2 and consisted of focal loss from basal and/or lateral cell membranes and localization in the cell cytoplasm. Only rarely was Na,K-ATPase localized to the apical cell membrane. After the removal of Phenol II, cystic tubular cells, BM, and Na,K-ATPase returned to normal. Thus, in this model of polycystic kidney disease, initial cyst formation occurred in tandem with BM structural change whereas cell proliferation and altered location of Na,K-ATPase occurred after the appearance of cysts.
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PMID:Sequential tubular cell and basement membrane changes in polycystic kidney disease. 132 61

Investigations to determine the inhibitory activity on the Ca(2+)-transport-ATPase of human erythrocyte membranes were performed with various compounds of toxicological significance, mostly chlorinated and mainly used as biocides, such as phenol, 4-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol, 3,4-dichlorophenol, 2,3,4-trichlorophenol, 2,3,4,5-tetrachlorophenol, pentachlorophenol (PCP), captan, folpet, captafol, (+)-camphene, toxaphene, dichlorodiphenyltrichloroethane (DDT), lindane, endrin, dieldrin, alpha-endosulfan, beta-endosulfan, paraquat, diallate, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). Some of the compounds investigated display an inhibitory effect on the Ca(2+)-transport-ATPase at very low concentrations. The in vitro results obtained in this enzyme assay can be correlated directly with the results of other in vitro assays and with the results of in vivo investigations in different species in which an inhibitory effect on various biological functions is observed. Therefore, an inhibitory effect on the Ca(2+)-transport-ATPase indicates a toxic effect of these compounds to cell functions. Since the inhibitory effect of these compounds can be measured rapidly and the enzyme is easy to handle, it might be a useful tool to screen the toxic effects of various compounds on cell function. The aim of the authors was to investigate the usefulness of this screening test system for the characterization of the cellular toxicity of various compounds.
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PMID:The Ca(2+)-transport-ATPase of human erythrocytes as an in vitro toxicity test system--acute effects of some chlorinated compounds. 144 81

A high molecular weight (HMW) fraction of the 150,000 g supernatant of rat brain homogenates contains protein-tRNA complexes which are able to incorporate [3H]Arg and [3H]Lys into tRNA. The aminoacylation of tRNA(Arg) was found to be dependent on ATP and inhibited by RNase. Conversely, the aminoacylation of tRNA(Lys) did not require exogenous ATP and was resistant to RNase and ATPase. In HMW fractions of regenerating rat sciatic nerves, the charging of both tRNA(Arg) and tRNA(Lys) was resistant to RNase and ATPase and did not require exogenous ATP. Because sciatic nerves are rich in axoplasm and tRNAs are known to be present in axons, we tested the hypothesis that degradative enzyme-resistant, ATP-tRNA complexes were of axonal origin. In HMW fractions from rat liver (containing no axons), both tRNA(Arg) and tRNA(Lys) were sensitive to RNase and required exogenous ATP for charging. But, in similar fractions of axoplasm obtained from the giant axon of squid, both tRNAs were insensitive to RNase and ATPase and did not require exogenous ATP for charging. These results suggest that tRNAs in axons are present in protected HMW complexes and contain endogenous stores of ATP. The presence of ATP in the HMW complexes was demonstrated by the luciferase-luciferin assay for ATP. The nature of the protection of tRNAs from RNases was examined by dissociating proteins from HMW complexes by boiling, treating with proteinase K, or overhomogenizing the tissue. These procedures failed to render brain tRNA(Lys) susceptible to RNase. But phenol-extracted, ethanol-precipitated brain tRNA(Lys) was sensitive to RNase, suggesting that the protection of tRNA(Lys) may be by a protease- and heat-resistant polypeptide or by a nonproteinaceous mechanism.
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PMID:Evidence that axonal tRNAs are resistant to RNase and ATPase and can be aminoacylated in the absence of exogenous ATP. 153 73

Renal nerve activity increases (Na+, K+)-ATPase activity and contributes to the development of hypertension in young SHR. The present study was designed to examine the effect of sodium intake on blood pressure and proximal tubule solute reabsorption in sham-operated or renal denervated, 5-week old SHR and WKY. Three-week old SHR and WKY rats underwent sham surgery or renal denervation with 10% phenol and were maintained for 10 days on either a 0.6% or 2.2% NaCl diet. Blood pressure was obtained by indirect tail cuff measurements during this interval. Of the eight groups, only sham-operated SHR on a high sodium diet had hypertension, 122.0 +/- 4.2 mm Hg vs. 98.7 +/- 3.3 mm Hg (mean for remaining groups). Renal plasma flow (RPF), glomerular filtration rate (GFR), and the fractional excretion of lithium (FELi) were determined in rats maintained on a 2.2% sodium diet at 5 weeks of age. FELi was less in sham-operated SHR, 5.3 +/- 0.7%, compared to WKY, 9.4 +/- 2.8% (P less than 0.02). Furthermore, denervation ameliorated the reduced FELi in SHR, 10.2 +/- 1.2%, without affecting FELi in WKY. RPF and GFR were similar between sham-operated and renal denervated SHR and WKY. No significant difference could be detected in net sodium balance between WKY and SHR during this period. These findings demonstrate 1) from the basis of FELi, young SHR, of this strain, exhibit enhanced proximal tubule solute reabsorption and hypertension while on a high sodium diet and, 2) renal denervation ameliorates both the enhanced proximal tubule solute reabsorption and the early development of hypertension. These data support the concept that renal nerve activity of young SHR is augmented and contributes to the development of hypertension by enhancing salt retention.
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PMID:Renal nerve-mediated proximal tubule solute reabsorption contributes to hypertension in spontaneously hypertensive rats. 162 13

The role of the mammalian mesonephric kidney is not completely understood. It has been established that outpouchings of the mesonephric excretory ducts give origin to parts of the urogenital system of the adult. It is also known that mammalian mesonephric urine is formed as an ultrafiltrate. The mesonephric renal tubules have Na+/K+ adenosine triphosphatase (Na+/K+ pump), secrete phenol red, and reabsorb protein. Prior to this work, the possibility of epithelial transport of ions and metabolic substrates across mammalian mesonephric tubules had not been directly evaluated. Proximal mesonephric tubules obtained from 17 to 18-days-old rabbit embryos were isolated and perfused in vitro. Continuous intracellular electrical recordings were obtained with Ling-Gerard-type microelectrodes and a high input impedance electrometer. In tubules perfused and bathed in standard mammalian Ringer's solutions, the average transmembrane electrical cell potential difference (PD) was -43 +/- 0.5 mV (76 cells). The cellular PD decreased by 30 percent when the temperature of the bath was cooled from 37 degrees C to 30 degrees C. The cells also depolarized by 25 percent in the first five minutes of exposure to 0.1 mM ouabain. In addition, the cell PD decreased by 40 and 60 percent when the extracellular potassium concentration was raised from five to 25 and 50 mM, respectively. The uptake of glucose and alanine was similarly electrogenic (delta:1 mV/mM). The cell PD, the K+ conductance, and the electrogenicity induced by luminal exposure to 5 mM glucose or alanine are significantly lower in the mesonephric as compared to the metanephric proximal tubules of the rabbit. These observations suggest that sodium-coupled transepithelial transport mechanisms, driven by the Na+/K+ pump, are already present in the mammalian mesonephric proximal tubule. Increases in the number of Na+/K+ pumps, conductive K+ channels, and sodium-substrate cotransporters seem to be at the core of proximal tubular ontogeny.
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PMID:Renal ontogeny: epithelial transport in the mammalian mesonephric proximal tubule. 164 30

The outer membranes (OMs) from serovars a, b, and c of Treponema denticola, originally isolated from periodontal patients, were prepared. Dialysis of the OMs against 20 mM MgCl2 yielded the aggregable (A) and the nonaggregable (NA) moieties of the OMs. The absence of muramic acid, adenosine triphosphatase, hexokinase, and nucleic acid as well as electron microscopy indicated that the OM preparations were homogeneous. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the A and NA moieties of the OMs showed approximately 25 Coomassie brilliant blue R-250 stain-positive bands or 47 silver-stained polypeptides. The relative molecular masses ranged between 14 and 97 kDa. The electrophoretic polypeptide profiles of the A and NA moieties shared many similarities among serovars a, b, and c. However, they exhibited variation in the overall pattern, intensity, or location of the polypeptide stained zones. This was especially true for serovar b. Two-dimensional electrophoretic studies showed an excess of 100 silver-stained spots with isoelectric points of 4.6 to 7.0 and relative molecular masses in the 14- to 97-kDa range. The OMs contained simple proteins, glycoproteins, and lipoproteins. The NA moieties of the OMs contained 4 to 6, 10 to 12, and 4 to 6 glycopeptides as well as two, seven, and two lipoprotein bands for serovars a, b, and c, respectively. The A moieties of the OMs showed 7 to 9, 11 to 13 and 5 to 6 glycopeptides as well as four, five, and three lipoprotein bands for serovars a, b, and c, respectively. Lipopolysaccharide was detected in the OMs of the three serovars following removal of proteins with proteinase K, pronase and silver staining of sodium dodecyl sulfate-polyacrylamide gels, or removal of lipopolysaccharide from the OMs by hot phenol extraction. The 66- and 53-kDa bands were present in serovars b and c, while a band with a relative molecular mass of 45 kDa was present only in serovar c. Endotoxin-like activity was also shown in the OMs of the three serovars by the Limulus amebocyte clotting assay and the chick embryo lethality test. This is the first report on selected biochemical properties of the OM macromolecules of three known serovars of T. denticola.
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PMID:Biochemical properties of the outer membrane of Treponema denticola. 171 83


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