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)

Specific assays for 5'-nucleotidase, adenosine diphosphatase (ADPase) and Mg2+-dependent adenosine triphosphatase (Mg2+-ATPase) have been optimized for human lymphocytes and their subcellular localizations determined by sucrose density gradient centrifugation. 5'-Nucleotidase was localized solely to the plasma membrane of the lymphocyte. ADPase activity has been shown to have a dual localization to the plasma membrane and mitochondria, whilst Mg2+-ATPase was mainly located in the mitochondria. No [Na+,K+] activated Mg2+-dependent ATPase could be measured in these cells. We have confirmed the striking decrease in the specific activity of 5'-nucleotidase activity in lymphocytes from patients with common variable primary hypogammaglobulinaemia. In contrast, the specific activities of ADPase and Mg2+-ATPase showed no alteration in lymphocytes from the patient group when compared to controls. Thus the deficiency of ecto-5'-nucleotidase in the lymphocytes of patients with hypogammaglobulinaemia is a highly selective defect in purine metabolism.
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PMID:Studies on the kinetic properties and subcellular localization of adenine nucleotide phosphatases in peripheral blood lymphocytes from control subjects and patients with common variable primary hypogammaglobulinaemia. 612 80

We have previously shown that Na+-K+ pump activity (ouabain-sensitive 86Rb uptake) is decreased in vascular tissue of animals with various forms of low renin hypertension. In the present study we measured Na+-K+-ATPase activity, the energy source for Na+-K+ pumping, in membrane fractions prepared from myocardial tissue of rats with chronic one-kidney, one-clip hypertension and their one-kidney normotensive controls. Membranes were prepared by two independent methods: microsomal fractions (method 1) and fractions prepared by the hypotonic LiBr method of Dhalla et al. (method 2). In membranes prepared from left ventricles of the hypertensive rats (by method 1) Na+-K+-ATPase activity was decreased, Mg2+-ATPase activity was increased, and the sialic acid content and 5'-nucleotidase activity (two putative membrane markers) were unchanged relative to the control rats. The sensitivity of cardiac Na+-K+-ATPase to inhibition by ouabain was also unchanged. Na+-K+-ATPase activity was also decreased in the right ventricles (method 1) of these hypertensive rats, suggesting that this defect is probably not pressure related. In membranes prepared from the left ventricles of the hypertensive rats by method 2, Na+-K+-ATPase activity was again reduced, whereas the Mg2+-ATPase and 5'-nucleotidase activities were unchanged relative to the controls. These studies suggest that myocardial Na+-K+-ATPase activity is suppressed in rats with this low renin form of hypertension and the possible effect of this suppression on myocardial contractile activity is discussed.
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PMID:Decreased myocardial Na+-K+-ATPase activity in one-kidney, one-clip hypertensive rats. 613 90

A high affinity Ca2+-stimulated, Mg2+-dependent ATPase (Ca2+-Mg2+-ATPase) was identified in microsomes and plasma membrane vesicles isolated from rat hepatocytes. The distribution of this enzyme was similar to that of the plasma membrane marker enzymes alkaline phosphodiesterase and 5'-nucleotidase. The Ca2+-Mg2+-ATPase had an apparent half-saturation constant of approximately 75 nM for Ca2+. After incubation of rat hepatocytes with 25 nM vasopressin for 3 min, the activity of Ca2+-Mg2+-ATPase was decreased 15-30%. The effect of vasopressin on the activity of this enzyme was near maximal after incubating hepatocytes with vasopressin for only 15 sec. The concentration of vasopressin needed for half-maximal inhibition of this enzyme in hepatocytes was approximately 6 nM. Treatment of the hepatocytes with 10 microM phenylephrine caused about a 10% decrease in ATPase activity while 10 nM glucagon or 200 microU/ml insulin did not affect the enzyme. These findings suggest that inhibition of the Ca2+-Mg2+-ATPase activity may be part of the mechanism by which vasopressin and alpha-adrenergic agonists elevate cytosolic Ca2+ in hepatocytes.
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PMID:Regulation of Ca2+-Mg2+-ATPase activity in hepatocyte plasma membranes by vasopressin and phenylephrine. 613 76

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

The lipid composition and fluidity of plasma membranes have been studied at different stages of liver regeneration (4, 15 and 24 h after surgery). The phospholipid and fatty acid composition is not modified, whereas the cholesterol/phospholipid ratio is lower with respect to control membranes. The modification of the physical properties of the membranes has been studied directly by EPR analysis and indirectly by temperature dependence and cooperativity of some membrane-bound enzymes (Mg2+-ATPase, (Na+ + K+)-ATPase and 5'nucleotidase). Surgical operation or anaesthesia alone causes an early increase in fluidity; such an effect appears to be markedly reduced at a later stage. There seems to be a marked effect of regeneration on plasma membrane fluidity 15 h after partial hepatectomy when several parameters--surface fluidity, cholesterol/phospholipid ratio, and 5'-nucleotidase activity in the presence of concanavalin A -- are modified and indicate an increase in membrane fluidity. It is suggested that this modification of membrane properties could be related to the proliferative process.
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PMID:Plasma membrane changes associated with rat liver regeneration. 624 90

The sarcolemmal membranes were isolated by the hypotonic shock-LiBr treatment method from rat, guinea pig, rabbit, and dog hearts and their various biochemical activities were measured. The Mg2+-ATPase, Ca2+-ATPase, and 5'-nucleotidase were most active in rat heart homogenates as well as sarcolemmal membranes, whereas the adenylate cyclase and Na+, K+-ATPase were most active in guinea pig heart preparations. ATP-independent calcium binding activity of rat heart sarcolemma was the same as that of guinea pig heart membrane, whereas ATP-dependent calcium binding of rat heart preparation was negligible. Treatment of sarcolemma with 0.6 M KCl increased the adenylate cyclase and Na+, K+-ATPase activity in rat heart, but these activities were unaltered or decreased in other species. The gel electrophoretic pattern of protein bands and phospholipid composition of rat heart sarcolemma were different from those of guinea pig heart. Sarcolemma isolated from hearts by sucrose gradient method also showed species-dependent difference in the membrane-bound enzyme activities. These results have been interpreted to suggest species-related difference in calcium movements across sarcolemma and this may contribute to determining species-dependent difference in the regulation of myocardial calcium metabolism.
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PMID:Species-related difference in the heart sarcolemmal enzyme activities. 624 42

Brain extracts from 8-day-old chick embryos have been shown to influence morphological development of dissociated brain cells from 7-day-old chick embryos in culture. Stimulatory effects on size of the neuronal somas and on growth of long processes were observed by adding the cytosol of the brain extract or the dialysate of the cytosol. These morphological changes parallel modifications of various enzyme activities according to the age of the cultures. Adenyl cyclase, (Na+,K+)- and Mg2+-ATPase, 5'-nucleotidase, choline acetyltransferase, and acetylcholinesterase activities were studied between 5 and 14 days of culture. Adenyl cyclase activity was strongly stimulated at 8 days by both extracts. (Na+,K+)- and Mg2+-ATPase activities were stimulated in 8-day-old cultures only by the dialysate. 5'-Nucleotidase activity was stimulated in 8-day-old cultures by the dialysate and in 11-day-old cultures by both extracts. Choline acetyltransferase activity was stimulated by the cytosol in 8-day-old cultures and by the dialysate in 11-day-old cultures. The total acetylcholinesterase activity was higher in 8-, 11-, and 14-day-old cultures treated with the cytosol. When the cells were treated with the dialysate, the activity was only higher in 14-day-old cultures. We also found that following the addition of brain extracts, the specific activity of the enzymes we studied was enhanced and became close to the values found in vivo during embryogenesis. Thus in parallel to the morphological modifications observed in nerve cell cultures treated by embryo brain extracts, biochemical variations especially involved in synaptogenesis and membrane development could be measured.
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PMID:Study of some enzyme activities in cultured chick embryo brain nerve cells treated by chick embryo brain extracts. 625 93

A method is offered for isolation of subcellular fractions from small intestinal smooth muscle cells enriched by plasma membranes (PM). The method is based on differential centrifugation over sucrose density gradient. According to the localization of marker enzymes, the membrane fraction obtained with the use of 30% sucrose is considered to be optimal. The PM fraction is superior to the homogenate 10-fold on the average in the magnitude of Na, K-ATPase, 17-fold in Mg2+-ATPase, and 15-fold in that of 5'-nucleotidase activity. ATPase of PM is activated by Ca2+ in micro- and millimolar concentrations. It is suggested that Mg2+-dependent Ca-activated ATPase of PM is related to the Ca2+ content control in the cell.
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PMID:[Extraction of plasma membranes from smooth muscle cells of the rabbit small intestine]. 636 47

Plasma membranes were isolated from normal thymocytes of Wistar-King-A rats and from Moloney virus-induced rat thymic leukemias (RML11 and RML30 cells) using a simplified method developed by us. All the isolated plasma membranes were electron-microscopically pure and enriched in the specific activities of (Na+ + K+)-ATPase, Mg2+-ATPase and 5'-nucleotidase in comparison with those of the corresponding whole cell homogenates. These plasma membranes as well as the original cells were analyzed for phopholipid composition and contents of phospholipid, cholesterol and plasmalogen. There was no difference in the phospholipid composition among the three plasma membranes. However, all the plasma membranes were deficient in sphingomyelin, namely, 1.8% for the normal thymocytes, 2.2% for the RML11 cells and 1.9% for the RML30 cells as percentage of the total phospholipid phosphorus. The contents of phospholipid (mumol per mg protein), cholesterol (mumol per mg protein) and plasmalogen (mol% to phospholipid) of the plasma membranes from both lines of malignant cells were lower than those of the normal thymocyte membranes. The molar ratio of cholesterol to phospholipid of the malignant cell membranes was also lower than that of the normal membranes, because in the former membranes the degree of decrease in the cholesterol content was higher than that in phospholipid content.
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PMID:Lipids of plasma membranes from rat thymic lymphoid cells: deficiency of sphingomyelin. 696 38

Plasma membranes were isolated from lactating bovine mammary gland. Two crude membrane fractions; medium/d 1.033 (light membrane) and 1.033/1.053 interfaces (heavy membrane), were obtained by Ficoll density gradient centrifugation of osmotically washed microsomal fraction. Two crude membranes were further purified separately by sucrose density gradient centrifugation. Both light and heavy membranes banded at a sucrose density of 1.14. The purified membranes appeared as heterogeneous smooth membrane vesicles on electron microscopy. The contaminating suborganelles were not detected. The yield of the purified membranes relative to the homogenate was 1.2%. The degree of purity of the membranes was shown by a great increase in the specific activity of 5'-nucleotidase over the homogenate of 20-fold for light membrane and of 16-fold for heavy membrane. The relative activities of Mg2+-ATPase, (Na+ + K+)-ATPase, gamma-glutamyl transpeptidase, phosphodiesterase I, alkaline phosphatase and xanthine oxidase were also high (12-18-times) and nearly 20% of these enzymes was recovered. The activity of marker enzyme for mitochondria, endoplasmic reticulum and Golgi apparatus was very low, while that of acid phosphatase for lysosome was relatively high (5-times). DNA and RNA contents were very low. The major polypeptides rich in other suborganelles were not detected profoundly in the membrane fraction and the polypeptide composition in both light and heavy membranes were similar upon SDS-polyacrylamide gel electorphoresis.
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PMID:Isolation and characterization of plasma membrane from lactating bovine mammary gland. 720 55


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