Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.3.1 (Mg2+-ATPase)
1,484 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The microsomal (H+,K+)-ATPase systems from dog and pig fundic mucosa were purified to homogeneity and partially characterized. The method involves sodium dodecyl sulfate (SDS) (0.033% w/v) extraction of the microsomal non-ATPase proteins under appropriate conditions followed by sucrose density gradient centrifugation. Two distinct membrane bands of low (buoyant density = 1.08 g/mL) and high (buoyant density = 1.114 g/mL) densities having distinct enzymatic and chemical composition were harvested. The low-density membrane was highly enriched in Mg2+- or Ca2+-stimulated ATPase and 5'-nucleotidase activities but totally devoid of (H+,K+)-ATPase and K+-p-nitrophenylphosphatase activities. The latter two activities were found exclusively in the high-density membrane. SDS-polyacrylamide gel electrophoresis revealed the high-density membranes to consist primarily of a major 100-kilodalton (kDa) protein and a minor 85-kDa glycoprotein, the former being the catalytic subunit of the (H+,K+)-ATPase. The amino acid composition of the pure dog (H+,K+)-ATPase revealed close similarities with that from pig. The N-terminal amino acid was identified to be lysine as the sole residue. Similar to the high-density membrane-associated pure (H+,K+)-ATPase, the low-density membranes containing high Mg2+-ATPase activity also contained a 100-kDa peptide and a 85-kDa glycopeptide in addition to numerous low molecular weight peptides. Also, similar to the pure (H+,K+)-ATPase, the Mg2+-ATPase-rich fraction produced an E approximately P unstable to hydroxylamine and partially (about 25%) sensitive to K+ but having a slow turnover. The levels of E approximately P produced by the pure (H+,K+)-ATPase- and Mg2+-ATPase-rich fractions were 1400 and 178 pmol/mg of protein, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Purification and partial characterization of the (H+,K+)-transporting adenosinetriphosphatase from fundic mucosa. 282 83

The soluble fraction of uterine tissue was found to contain a factor which is a potent activator of various cyclic nucleotide phosphodiesterases (with the exception of the retinal photoreceptor cell enzyme). The protein origin of this factor was established, using proteolysis, precipitation with trichloroacetic acid. The activator was purified by gel filtration on Sephadex G-25 and Biogel P-4 as well as by a highly effective liquid chromatography. The activator was shown to be a peptide with Mr = 1150 Da. The peptide was thermostable and stable within a broad range of pH. Besides phosphodiesterases, the peptide activated 5'-nucleotidase and Mg2+-ATPase of photoreceptor membranes.
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PMID:[Detection of peptide, an activator of cyclic nucleotide phosphodiesterases, in uterine tissue]. 282 12

Sodium-potassium adenosinetriphosphatase (Na+-K+-ATPase) is modulated by functional demands. We determine whether Na+-K+-ATPase specific activity was changed by oral administration of different bile salts and whether upregulation in the liver is due to increased numbers of catalytic units. In rats after bile duct drainage for 18 h, Na+-K+-ATPase activity was reduced to 50% of control in liver and ileum but unchanged in jejunum and kidney. Increased Na+-K+-ATPase activity after short-term feeding of bile salts was noted only following trihydroxy bile salts, i.e., taurocholate (100 mg/100 g body wt) increased hepatic Na+-K+-ATPase 143% and ileum 138% above control, whereas jejunum and kidney were unchanged. Chronic feeding of trihydroxy bile salts for 4 days increased hepatic Na+-K+-ATPase (214-260%) and alkaline phosphatase (189-274%), whereas 5'-nucleotidase and Mg2+-ATPase activities were unchanged from control. Plasma membrane Na+-K+-ATPase activity significantly increased as early as 4 h after taurocholate administration, whereas homogenate activity did not rise until 16 h; both reached a new steady state between 24 and 48 h. Sixteen hours after bile salt feeding, increased Na+-K+-ATPase activity was blocked by cycloheximide, and in the liver increased enzyme activity (179%) was associated with a comparable change in sodium-dependent [gamma-32P]ATP binding (162%) to liver plasma membrane fractions. These studies show Na+-K+-ATPase activity adapts selectively in liver and ileum following administration of trihydroxy bile salts, and the process involves increased density of Na+-K+ pump sites on the liver plasma membrane.
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PMID:Selective modulation of hepatic and ileal Na+-K+-ATPase by bile salts in the rat. 283 64

The sensitivity to photodynamic treatment of three plasma membrane enzymes in R3230AC mammary adenocarcinomas was assessed. The activities of Na+K+-ATPase, Mg2+-ATPase and 5'-nucleotidase in isolated membranes were measured after exposure of membranes to either hematoporphyrin derivative or Photofrin II plus light in vitro or in tumor membranes prepared from animals previously injected with 25 mg/kg Photofrin II and sacrificed at various times prior to exposure to light (in vivo-in vitro protocol). The activities of both Na+K+-ATPase and Mg2+-ATPase were inhibited at equivalent rates by Photofrin II in vitro; inhibition was drug dose and light dose related. For 5'-nucleotidase in vitro, a 10-fold higher porphyrin concentration was required to achieve a similar rate of enzyme inhibition as that for the ion-activated ATPases. Injection of Photofrin II in vivo followed by preparation of tumor plasma membranes, which were subsequently exposed to light in vitro, produced no photosensitization of 5'-nucleotidase activity at any time studied (up to 72 h after Photofrin II administration). Under the same conditions Na+K+-ATPase activity was reduced by 40-60% from 2 to 72 h after drug injection, whereas Mg2+-ATPase activity was inhibited by 10-25% over the same time course. The differential sensitivity of these three enzymes observed in this in vivo-in vitro protocol suggests that each enzyme may possess different characteristics, such as three-dimensional configuration or membrane location, that afford varying susceptibility to porphyrin photosensitization. The data also suggest that photosensitivity-induced damage to these ion-activated plasma membrane ATPases could have deleterious effects on tumor cell survival.
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PMID:Photosensitizing effects of hematoporphyrin derivative and photofrin II on the plasma membrane enzymes 5'-nucleotidase, Na+K+-ATPase, and Mg2+-ATPase in R3230AC mammary adenocarcinomas. 283 53

1. We performed an enzymatic characterization of two different fractionation procedures of ventricles from rat hearts. The enzymatic assays covered succinic dehydrogenase as a marker for inner mitochondrial membranes, monoamine oxidase as a marker for outer mitochondrial membranes, NADPH-cytochrome c reductase and RNA as endoplasmatic reticular markers, acid phosphatase as a lysosomal marker, and lactic dehydrogenase as a marker for the "soluble" compartment; DNA was estimated for nuclear contamination. 2. The plasma membrane markers 5'-nucleotidase, Ca2+-ATPase, Mg2+-ATPase, Na+-K+-ATPase, and adenylate cyclase were determined. 3. The roughly prepared membrane fractions showed increased yields of the membrane markers; the number of beta receptors, determined with (-)-[3H] dihydroalprenolol and DL-propranolol, amounted to 68 +/- 6 fmol/mg protein (KD = 3390 +/- 450 pmol, Hill coefficient = 1.5). 4. The membrane fraction prepared with a linear sucrose gradient showed an increased inner mitochondrial membrane marker; presumably the outer mitochondrial membrane was stripped off. The beta-receptor number was 39 +/- 3 fmol/mg protein (KD = 6250 +/- 300 pmol; Hill coefficient = 1.2).
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PMID:Beta-adrenergic receptors and enzymes in rat myocardial membranes: implications of fractionation procedures and beta-adrenoceptor antagonists. 284 52

Separation of the gradient-purified gastric microsome into two membrane subfractions of distinct enzymatic and phospholipid composition has been achieved by mild SDS (0.033% w/v) treatment followed by sucrose gradient centrifugation of the pig and rabbit gastric microsomes. While the high-density membranes had all of the (H+,K+)-ATPase and K+-pNPPase activities and revealed a single major 100-kDa band on SDS-PAGE, the low-density membranes contained all of the 5'-nucleotidase and nearly all of the Mg2+-ATPase. In the present study, the low-density subfraction has been characterized to be derived from the apical membranes and the high-density one from the intracellular tubulovesicular membranes of the parietal cells. Such characterization was based primarily on sole dependency of the apical plasma membranes on the endogenous activator for (H+,K+)-ATPase activity, differential sensitivity of the activator (AF)-dependent and -independent (H+,K+)-ATPase on micromolar vanadate and Ca2+, specific vitamin B12 binding ability of the apical plasmalemma, phospholipid and protein profiles of the two membrane subfractions, and other parameters. The AF, mentioned previously, has recently been implicated as a cytosolic regulator of the gastric (H+,K+)-ATPase [Bandopadhyay et al. (1987) J. Biol. Chem. 262, 5664-5670]. Two different forms (i.e., AF-dependent and -independent forms) of the (H+,K+)-ATPase are suggested to be present in the tubulovesicles on the basis of differential vanadate sensitivity while the AF-dependent form alone is present in the apical membranes. The data have been discussed in terms of stimulation-induced membrane transformation characteristic of the H+-secreting epithelia including the acid-secreting cells of the stomach.
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PMID:Characteristics of the isolated apical plasmalemma and intracellular tubulovesicles of the gastric acid secreting cells: demonstration of secretagogue-induced membrane mobilization. 285 60

Myometrial plasma membrane (MPM) preparations from rats treated with oestradiol were obtained by discontinuous sucrose-gradient centrifugation. The preparations contained calcium-stimulated and magnesium-dependent ATPase (Ca2+/Mg2+-ATPase). A dramatic decrease in the activity of Ca2+/Mg2+-ATPase was observed when preparations were treated with 0.025-10 mumol prostaglandins E2 and F2 alpha (PGE2 and PGF2 alpha)/l. In contrast, there was a marked increase in MPM-bound 5'-nucleotidase activity at low concentrations (up to 2 mumol/l) of PGE2 and PGF2 alpha; higher concentrations (up to 10 mumol/l), however, led to a progressive inhibition of enzyme activity. Association (specific and non-specific binding) of PGE2 and PGF2 alpha with MPM at pH 7 was found to require Ca2+ (half-maximal concentration approximately 0.7 mmol/l). Changes in the allosteric properties of MPM-bound 5'-nucleotidase by concanavalin A (as reflected by changes in the Hill coefficient) indicated a fluidization of the membrane induced by PGE2 and PGF2 alpha. The steady-state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene-labelled MPM decreased in PGE2- and PGF2 alpha-treated MPM from 1.24 +/- 0.04 (S.D.) to 0.66 +/- 0.01 and 0.74 +/- 0.01 respectively, which is consistent with a general increase in membrane fluidity. It is suggested that PGE2 and PGF2 alpha promote changes in the physical properties of MPM which may be relevant to the induction of uterine contractions by enzymatic regulation of intracellular calcium concentrations.
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PMID:Effect of prostaglandins E2 and F2 alpha on membrane calcium binding, Ca2+/Mg2+-ATPase activity and membrane fluidity in rat myometrial plasma membranes. 294 78

An estrogen-regulated arginine esteropeptidase is present in the immature rat uterus. The enzymatic complex consists of a membrane-bound activator and a soluble proenzyme. The activator is under strong estrogen control; its activity increases 10-fold 3 h after a single dose of 17 beta-estradiol. The subcellular localization of the activator is determined by a radioactive assay of fractions prepared by sucrose density centrifugation. The distribution of activity parallels the distribution of two plasma membrane markers, Mg2+-ATPase and 5'-nucleotidase. Electron micrographic visualization of the gradient fractions containing the activator reveals a population of vesicles 0.2-0.5 micron in diameter.
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PMID:Estradiol stimulates a uterine plasma membrane protease activator. 296 50

The purpose of this investigation was to determine which enzyme activities are true canine neutrophil plasma membrane markers. Three enzymes thought to be present on plasma membranes were chosen for study: 5'-nucleotidase, magnesium-dependent adenosine triphosphatase (Mg2+-ATPase), and leucine aminopeptidase. Both 5'-nucleotidase and Mg2+-ATPase were found to be ectoenzymes in the canine neutrophil but additional Mg2+-ATPase activity was located intracellularly. An endogenous inhibitor of 5'-nucleotidase was found in the cytosol of canine neutrophils. The specific 5'-nucleotidase inhibitor, adenosine 5'-[alpha, beta-methylene] diphosphate also inhibited the canine enzyme in intact cells. Leucine aminopeptidase was located solely in the myeloperoxidase-containing granules of the canine neutrophil. Plasma membrane, as identified by the presence of Mg2+-ATPase and 5'-nucleotidase activities, was separated from other cell organelles by Percoll-density gradient centrifugation of a 10 000 X g supernatant of nitrogen cavitated neutrophils.
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PMID:Canine neutrophil plasma membrane markers. 298 65

Mechanisms of alcoholic liver disease are still ill defined. We evaluated in two outbred lines of mice whether chronic ingestion of ethanol alters the lipid composition and/or enzyme activity of liver plasma membranes. Two mouse lines with different sensitivities towards the hypnotic effect of ethanol, designated long sleep and short sleep, were fed a liquid diet containing ethanol for 30 days. Ethanol intake reached 30 gm per kg per day in both lines, and serum ethanol levels were similar. In addition, hepatic triglyceride levels were similarly increased 2-fold with ethanol feeding. The following effects of ethanol treatment were observed in liver plasma membrane fractions: (i) Na+,K+-ATPase was significantly increased to 26% above control in long sleep only; (ii) alkaline phosphatase activity was 2-fold increased in both lines; (iii) 5'-nucleotidase, leucine aminopeptidase and Mg2+-ATPase activities remained unchanged in both lines; (iv) unesterified cholesterol and total phospholipid contents were unaltered in both lines, and (v) cholesteryl esters were increased in both lines, but to a greater extent in short sleep (1.5 vs. 4-fold). Thus, chronic ethanol ingestion induces specific alterations in liver plasma membrane structure and function, suggesting that adaptive responses to ethanol may be determined in part by inherited factors.
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PMID:Effect of chronic ethanol administration on enzyme and lipid properties of liver plasma membranes in long and short sleep mice. 299 Nov 3


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