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)

Cultures of osteoblastlike cells obtained from the endosteal surfaces of rabbit long bones formed and mineralized an extracellular matrix when they were supplied daily with medium containing fresh ascorbate. No matrix formed without this supplementation. The matrix mineralized whether or not beta-glycerophosphate, a substrate of alkaline phosphatase, was added to the medium. The ion-transporting ATPase activities of untreated, ascorbate-treated, and ascorbate plus beta-glycerophosphate-treated cells were measured. Ascorbate-treated and ascorbate plus beta-glycerophosphate-treated cells had similar enzyme activities. The activities of the Ca2+-ATPase; Ca2+,Mg2+-ATPase; and alkaline phosphatase in treated cells were elevated over the activities in untreated cells. Na+,K+-ATPase activity was lower in treated than in untreated cells. HCO3--ATPase activity was not changed by treatment. Alkaline phosphatase activity was 20 times higher in freshly isolated osteoblastlike cells than in cells grown to confluence in primary culture. In addition, subculturing further reduced the activity of this osteoblast-marker enzyme. The activities of the ion-transporting ATPases and alkaline phosphatase in second passage cells were similar to the activities of these enzymes in fresh, noncalcifying tissues. Nevertheless, second passage cells retain the ability to mineralize an extracellular matrix, and their ion-transporting ATPase and alkaline phosphatase activities are altered when the cells mineralize a matrix.
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PMID:Ion-transporting ATPases and matrix mineralization in cultured osteoblastlike cells. 609 28

Na+,K+-ATPase, HCO3(-)-ATPase, Ca2+,Mg2+,-ATPase, Ca2+-ATPase, and alkaline phosphatase activities were measured in cultures of osteoblastlike cells treated with fluoride and cortisol separately and in combinations. Low concentrations of cortisol increased HCO3- -ATPase (10(-11) to 10(-18) M cortisol) and alkaline phosphatase (10(-11) to 10(-9) M cortisol) activities, but higher cortisol concentrations reduced these activities. Na+,K+-ATPase, Ca2+,Mg2+-ATPase, and Ca2+-ATPase activities tended only to be reduced by cortisol. Fluoride (10(-6) and 5 X 10(-6) M) increased HCO3(-)-ATPase and alkaline phosphatase activities, but these activities were similar to controls in the presence of 10(-5) M fluoride. Ca2+,Mg2+-ATPase activity was decreased and Na+,K+-ATPase activity was increased as the concentration of fluoride increased (10(-6) to 10(-5) M). Preliminary experiments with fluoride indicated that lower concentrations (10(-7) M) were without effect. Cortisol concentrations of 10(-9) and 10(-8) M were chosen for studies with combinations of cortisol and fluoride because the effects of these concentrations on alkaline phosphatase activity were opposite, i.e. 10(-9) M increased whereas 10(-8) M decreased activity. Fluoride concentrations of 10(-6), 5 X 10(-6), and 10(-5) M were chosen because a peak of alkaline phosphatase activity occurred at 5 X 10(-6) M fluoride. Higher (10(-4) M) and lower (10(-7) M) fluoride concentrations were without effect. The effects of combinations of cortisol and fluoride depend on the enzyme activity measured. Fluoride (10(-6) M) combined with cortisol (10(-9) M) produced a peak of Na+,K+-ATPase activity. The increased activity obtained with all concentrations of fluoride alone was preserved when fluoride was combined with 10(-8) M cortisol, although the activity tended to be reduced at 5 X 10(-6) and 10(-5) M fluoride. HCO3(-)-ATPase activity was increased by fluoride combined with 10(-8) M cortisol and decreased by fluoride combined with 10(-9) M cortisol compared to the activities obtained with fluoride alone. The decrease in Ca2+,Mg2+-ATPase activity caused by fluoride alone was prevented by 10(-9) and enhanced by 10(-8) M cortisol, although all treatments produced the same activity at 10(-5) M fluoride. Ca2+-ATPase activity tended to be increased by combinations of fluoride and cortisol, but significantly so only at 10(-5) M fluoride in combinations with 10(-8) and 10(-9) M cortisol.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Effects of cortisol and fluoride on ion-transporting ATPase activities in cultured osteoblastlike cells. 609 29

A technique currently used for isolation of brush border membranes from renal and intestinal epithelium that involves vigorous tissue homogenization and sedimentation of non-luminal membranes in the presence of Mg2+ has been adapted to rat liver. Liver plasma membranes so prepared consisted almost exclusively of vesicles by electron microscopy, showed some contamination with endoplasmic reticulum and minimal contamination with mitochondria or Golgi by marker enzymes, were highly enriched in alkaline phosphatase, Mg2+-ATPase, and 5'-nucleotidase activity compared with homogenate, and showed little enrichment in (Na+, K+)-ATPase. Comparison of this enzymatic profile with cytochemical studies localizing (Na+, K+)-ATPase and alkaline phosphatase to the sinusoidal/lateral and canalicular membranes, respectively, suggested that these membranes were predominantly of canalicular origin. They had a lower (Na+ + K+)-ATPase specific activity, lower lipid content, and higher cholesterol to phospholipid molar ratio than a conventional plasma membrane preparation believed to be enriched in canaliculi. Moreover, it was possible to measure movement of D-[3H]glucose into an osmotically sensitive space bounded by these membrane vesicles.
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PMID:Isolation of a rat liver plasma membrane fraction of probable canalicular origin. Preparative technique, enzymatic profile, composition, and solute transport. 611 3

Phosphate deficiency imposed on weanling rats for two wk resulted in a 40% increase in alkaline phosphatase activity of incisor pulp, without a significant change in Ca2+-, Mg2+-ATPase activity. The results are consistent with a separate identity for the two enzymes, but their physiological roles remain obscure.
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PMID:Effect of phosphate deficiency on pulp alkaline phosphatase and Ca2+-, Mg2+-ATPase activity in rats. 613 38

Highly purified plasma membranes of calf thymocytes were fractionated by means of affinity chromatography on concanavalin A-Sepharose into two subfractions; one (fraction 1) eluted freely from the affinity column, the second (fraction 2) adhered specifically to concanavalin A-Sepharose. Previous analysis showed that both subfractions were right-side-out (Resch, K., Schneider, S. and Szamel, M. (1981) Anal. Biochem. 117, 282-292). The ratio of cholesterol to phospholipid was nearly identical in plasma membrane and both subfractions. When isolated plasma membranes were labelled with tritiated NaBH4, both subfractions exhibited identical specific radioactivities. After enzymatic radioiodination of thymocytes, the relative distribution of labelled proteins and externally exposed phospholipids was very similar in isolated plasma membranes and in both membrane subfractions, indicating the plasma membrane nature of the subfractions separated by affinity chromatography on concanavalin A-Sepharose. This finding was further substantiated by the nearly identical specific activities of some membrane-bound enzymes, Mg2+-ATPase, alkaline phosphatase and gamma-glutamyl transpeptidase. The specific activities of (Na+ + K+)-ATPase and of lysolecithin acyltransferase were several-fold enriched in fraction 2 compared to fraction 1, especially after rechromatography of fraction 1 on concanavalin A-Sepharose. Unseparated membrane vesicles contained two types of binding site for concanavalin A. In contrast, isolated subfractions showed a linear Scatchard plot; fraction 2 exhibited fewer binding sites for concanavalin A: the association constant was, however, 3.5-times higher than that measured in fraction 1. When plasma membranes isolated from concanavalin A-stimulated lymphocytes were separated by affinity chromatography, the yield of the two subfractions was similar to that of membranes from unstimulated lymphocytes. Upon stimulation with concanavalin A, Mg2+-ATPase, gamma-glutamyl transpeptidase and alkaline phosphatase were suppressed in their activities in both membrane subfractions. In contrast, the specific activities of (Na+ + K+)-ATPase and lysolecithin acyltransferase were enhanced preferentially in the adherent fraction (fraction 2). The data suggest the existence of domains in the plasma membrane of lymphocytes which are formed by a spatial and functional coupling of receptors with high affinity for concanavalin A, and certain membrane-bound enzymes, implicated in the initiation of lymphocyte activation.
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PMID:Characterization of functional domains of the lymphocyte plasma membrane. 613 98

Gentamicin and neomycin-resistant mutants of Escherichia coli K-12 were isolated some of which were resistant to nitrofurans, chlorate, P1 and lambda bacteriophages as well as to all aminoglycoside antibiotics tested. Previously isolated nitrofuran-resistant mutants were not cross-resistant to the tested aminoglycosides, chlorate and bacteriophages. The aminoglycoside-resistant mutants exhibiting cross-resistance had enhanced membrane Mg2+-ATPase and decreased periplasmic alkaline phosphatase activity compared to their parent sensitive strains. The mutants were also defective in the fermentation of sugars, reduction of nitrate and nitrite, and in formate dehydrogenase activity. Preliminary genetic studies indicated that the pleiotropic mutation might be located in the upper left quadrant of the E. coli K-12 chromosome linkage map. It is postulated that such mutants with gross membrane alterations have impaired accumulation of aminoglycoside and nitrofuran antibiotics.
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PMID:Gentamicin- and neomycin-resistant mutants of Escherichia coli K-12 cross-resistant to nitrofurans. 614 38

Administration of lindane at a dose of 20 mg/kg body weight/day for 15 days to male rats brought about marked growth retardation. Succinic dehydrogenase, Mg2+-ATPase and glucose-6-phosphatase activities were inhibited in different fractions of liver tissues. Mg2+-ATPase, alkaline phosphatase and NADH-dehydrogenase activities were also inhibited in the liver plasma membranes of the lindane treated animals. Stimulation of 5'-nucleotidase activity in liver plasma membrane was observed under lindane intoxication. Supplementation of L-ascorbic acid by separate oral administration to the lindane intoxicated rats neutralized the growth retardation and maintained almost normal values of all the enzymes studied.
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PMID:Protective effect of L-ascorbic acid in lindane intoxicated rats. 618 53

6-Tridecylresorcylic acid (TRA) isolated from a primula Lysimachia japonica Thunb. inhibited contraction of myofibrils, superprecipitation of myosin B, and ATPase activities of myosin and actomyosin prepared from rabbit skeletal muscle in a dose-dependent manner. The IC50 values in molarity of TRA were as follows: myosin (K+,EDTA)-ATPase, 3.5 X 10(-6); myosin Ca2+-ATPase, 3.5 X 10(-5); and actomyosin Mg2+-ATPase, 1.6 X 10(-5). The inhibition of ATPase activity of myofibrils by TRA was virtually reversed by washing with the fresh saline solution. Kinetic analysis of inhibitory effects of TRA suggests that the inhibition of (K+,EDTA)-ATPase activity of myosin or subfragment-1 is parabolic noncompetitive. TRA had no effect on alkaline phosphatase and choline acetyltransferase activities. TRA may provide a useful chemical tool for the study of the molecular mechanisms of actin-myosin contractile systems.
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PMID:6-Tridecylresorcylic acid, a novel ATPase inhibitor that blocks the contractile apparatus of skeletal muscle proteins. 623 63

Magnesium-dependent adenosine triphosphatase (Mg2+-ATPase) activities wee studied in human neutrophilic polymorphonuclear leucocytes. Kinetic studies on whole leucocyte homogenates produced curvilinear kinetics suggesting the presence of at least two forms of Mg2+-ATPase. Neutrophils were homogenized in isotonic sucrose and, after low-speed centrifugation, the supernatant was subjected to analytical subcellular fractionation. Gradient fractions were assayed for Mg2+-ATPase and for principal organelle marker enzymes. Mg2+-ATPase was distributed between the plasma membrane, mitochondrial and cytosol fractions. Kinetic and inhibitor studies on Mg2+-ATPase from each localization indicated the presence of three forms of the enzyme. The plasma membrane and mitochondrial activities had a Km value of 0.2 mmol/l for ATP, whilst the Km for the cytosolic enzyme was 1.8 mmol/l. Inhibitor studies showed further differences between the three enzymes. Neutrophils were isolated from control subjects, patients with chronic granulocytic leukaemia and patients in the third trimester of pregnancy. The specific activities (mUnits/mg protein) of Mg2+-ATPase, in contrast to those of alkaline phosphatase, were similar in all three patient groups. This result, together with the fractionation experiments and inhibitor studies, strongly suggest that the ATPase is not attributable to neutrophil alkaline phosphatase.
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PMID:Subcellular localization and properties of adenosine triphosphatase in human polymorphonuclear leucocytes. 645 79

A rapid method is described for the simultaneous preparation of both membranes of guinea-pig enterocytes, using simple differential centrifugation techniques. Basolateral membranes were purified on a Percoll gradient and the final yield of (Na+ + K+)-ATPase was 12.4% of the original activity with an enrichment factor of 12.6-fold. Purification of the brush-border fraction was achieved by a calcium-precipitation technique. The yield of alkaline phosphatase was 18.9% of the original activity with an enrichment of 17.5-fold. Both fractions could be obtained within 3 h of the original homogenization. The characteristics of the preparations were checked by negative-staining electron microscopy and by the determination of glucose uptake. The orientation of the basolateral vesicles was determined by measuring the Mg2+-ATPase and (Na+ + K+)-ATPase activities and the [3H]ouabain binding before and after treatment of the preparation with a mixture of deoxycholate and EDTA which transforms the vesicles into sheets. There was a 60% rise in (Na+ + K+)-ATPase activity and ouabain binding, but no change in Mg2+-ATPase activity. It was therefore concluded that 60% of the original preparation consisted of inside-out vesicles and 40% of membrane sheets.
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PMID:The simultaneous preparation of basolateral and brush-border membrane vesicles from guinea-pig intestinal epithelium, and the determination of the orientation of the basolateral vesicles. 709 80


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