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:3.1.3.5 (5'-nucleotidase)
3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Enzymopathies are described concerning the enzymes of the oxidative pentose phosphate pathway including the glutathion system, of the majority of glycolytic enzymes as well as of the ATPase, adenylate kinase and pyrimidine-5'-nucleotidase. The distribution and the frequency of the enzymopathies differ strongly in the various regions of the world. Glucose-6-phosphate dehydrogenase and pyruvate kinase show the highest frequency. The detected polymorphism of the pathological enzyme variants is one of the reasons for the fact that no correlation between the decrease of the catalytic activity and the severity of the anaemias has been found. For the identification of risk-groups more precise methods are necessary. Till now the detailed relationships between enzymopathy and non-spherocytic haemolytic anaemias are not clarified. Furthermore the molecular mechanism of the instability of pathological enzyme variants is not yet clear.
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PMID:[Enzyme deficient non-spherocytic hemolytic anemias]. 67 10

Methods have been developed for the isolation on a semi-micro scale of a plasma membrane-enriched fraction from rat islets of Langerhans. An important feature of these experiments is the use of 125I-labeled wheat germ agglutinin as a specific probe for plasma membrane-containing fractions. The partly purified plasma membrane fraction had a density in sucrose of about 1.10 and was enriched in the activities of 5'-nucleotidase, alkaline phosphatase, sodium-potassium, and magnesium-dependent ATPase and adenylate cyclase. It contained only very low levels of acid phosphatase, cytochrome c oxidase, insulin, and RNA. Further purification was hampered by the relatively small amounts of fresh plasma membrane material that could be obtained from 16-24 rats in each experiment. When islets were prelabeled with radioactive fucose, the plasma membrane-enriched fraction contained radioactivity at a four- to fivefold higher specific acivity than the whole islet homogenate. Sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis of plasma membrane-enriched fractions pooled from several experiments revealed a distinctive pattern of protein bands as compared with other less pure fractions. With respect to rapidity, apparent specificity, and easy reversibility of the labeling of the plasma membrane fraction, 125I-wheat germ agglutinin provides a highly useful tool for the detection of microgram quantities of plasma membrane components which should be applicable to many other systems as well.
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PMID:Preparation and characterization of plasma membrane-enriched fractions from rat pancreatic islets. 79 56

Two subfractions of bovine thyroid plasma membranes, light membranes (L-membranes) and heavy membranes (H-membranes), were obtained by a discontinuous sucrose gradient centrifugation of plasma membranes. Electron microscopy of the plasma membrane and its subfractions showed that the H-membranes were very similar to the plasma membrane fraction, both contained junctional complexes, long membrane sheets, and vesicles. In contrast, the L-membranes consisted mainly of short membrane sheets and vesicles, and only a few junctional complexes. The H-membranes had greater adenylate cyclase activity which responded to thyroid-stimulating hormone (TSH) while this hormone had very little effect on the enzyme activity in the L-membranes. Despite the marked difference in TSH stimulation of adenylate cyclase activity in the H- and L-membrane fractions, specific binding of 125I-TSH was similar in both fractions. The L-membranes had higher specific activities of 5'-nucleotidase and Mg2+ATPase while (Na+ + K+)-ATPase and alkaline phosphatase activities were similar in the two subfractions. Protein kinase activity of H-membranes was not significantly stimulated by exogenous cyclic adenosine 3':5'-monophosphate (cAMP). Plasma membranes and H-membranes contained a substrate capable of being phosphorylated. Such phosphorylation was slightly increased by addition of soluble protein kinase. The phosphorylation of exogenous histone by protein kinase of plasma membranes and H-membranes was augmented by cAMP. In contrast, L-membranes had very little protein kinase activity even when exogenous histone was added. They were not a very good substrate for cytosolic protein kinase.
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PMID:Preparation and characterization of subfractions of bovine thyroid plasma membranes. 85 12

Glycerol (50%, w/w) was found to cause blistering of chick primary myoblast and fibroblast plasma membranes and extensive blistering of 5--6-day-old-myotube plasma plasma membranes in tissue culture. The tips of myoblasts and fibroblasts appeared to be the most sensitive portion of the plasma membrane to the blistering effect of glycerol. The glycerol-induced blistering of myotubes was reduced and delayed by brief EDTA pretreatment. Glycerol treatment (50, 15 and 8% sequentially) of myotubes was used to remove plasma membrane blisters and a plasma membrane-enriched fraction was isolated from these blisters using a modified Dextran T500-polyethylene-glycol 6000 aqueous two-phase polymer system. This fraction was found to be enriched 4.1-fold for 5'-nucleotidase activity, but not for other putative plasma membrane markers, (Na+ + K+)-ATPase activity or alpha-[125I]bungarotoxin binding material. Autoradiographs of alpha-[125I]bungarotoxin, glycerol-treated (50%, w/w) myotubes showed the plasma membrane blisters to be devoid of reduced silver grains. 5'-Nucleotidase was shown to be an ectoenzyme on myoblasts and 5-day-old myotubes and the total cellular activity was present on the cell surface. During the period of myoblast fusion and myotube formation, cell surface activity decreased to a low level while total cellular activity was elevated.
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PMID:Separation of plasma membrane markers by glycerol-induced blistering of muscle cells. 87 40

Human erythrocyte ghosts were solubilized in a low ionic strength medium containing 1% Triton X-100 and subjected to electrophoresis in polyacrylamide gels containing Triton X-100. Five major bands were stained with Coomassie Blue, all except one band being heterogenous when re-electrophoresed in gels containing sodium dodecyl sulphate. It was possible to detect acetylcholinesterase, non-specific esterase, ATPase, alkaline phosphatase, 5'-nucleotidase, glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase, and aldolase activities on the Triton-containing polyacrylamide gels. Two of the enzymes, ATPase and 5'-nucleotidase, showed substantial inhibition by Triton X-100 in quantitative studies. This appears to be a useful method for studying membrane enzymes in normal and pathological red cells.
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PMID:Polyacrylamide gel electrophoresis of human erythrocyte membrane enzymes solubilized with triton X-100. 89 Sep 65

Plasma membranes, microsomes, and mitochondria were isolated from mouse fibroblast (LM) suspension cells by modification of several established procedures. Choline analogues such as N,N'-dimethylethanolamine, N-monomethylethanolamine, or ethanolamine were incorporated in vivo into phospholipids of all three cell fractions studied, but to varying degrees depending on the type of analogue used. The in vivo incorporation of these bases into membrane phospholipids produced no significant effect on the activities of seven membrane-bound enzymes: (Na+, K+)-ATPase, 5'-nucleotidase (plasma membranes); TPNH-cytochrome c reductase, glucose-6-phosphatase, inosine diphosphatase (microsomes); and succinate cytochrome c reductase (mitochondria). The incorporation of base analogues into phospholipids was accompanied by several compensatory mechanisms. (a) The quantity of both phosphatidylcholine and phosphatidylethanolamine decreased up to 75% and 50% respectively in 3 days. (b) The molar ratio of desmosterol/phospholipid in the plasma membranes of LM cells grown in suspension culture in the presence of choline analogues decreased from 0.65 to 0.45. (c) The percentage of lysophosphatidylcholine increased over 2-fold in the phospholipid of all subcellular fractions studied. The quantity of lysophosphatidylcholine was directly proportional to the number of methyl groups on the nitrogen atom of the base analogue supplemented to the cells. This was a specific effect since the quantity of lysophosphatidylethanolamine, the other major lysophospholipid, remained unchanged. (d) The ratio of zwitterionic phospholipids to acidic phospholipids remained relatively constant in all isolated membrane fractions regardless of analogue supplementation. Neither increase in the degree of unsaturation nor shortening of fatty acid chain length was noted in response to analogue supplementation.
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PMID:Isolation and characterization of subcellular membranes with altered phospholipid composition from cultured fibroblasts. 95 75

The intracellular distribution of specific protease, plasminogen activator (PA), has been examined in Rous sarcoma virus-transformed chick embryo fibroblasts (RSV-CEF). Cellular homogenates were fractionated by differential centrifugation followed by sucrose gradient centrifugation. The activities and the percent distribution of a series of marker enzymes, specific for different subcellular organelles, were compared to those of PA. Normal CEF have been similarly fractionated and the relatively low amount of PA activity present in these cells has been analyzed in terms of its subcellular distribution. A membrane fraction was isolated from the RSV-CEF that contained the bulk of the PA activity and less than 8% of the total cellular protein. The specific activity of the PA in this fraction is 40-fold higher than that of a comparable fraction isolated from companion cultures of normal cells. This fraction contains little or no nuclear and cytoplasmic material and is contaminated only to a relatively small degree with mitochondria, lysosomes, endoplasmic reticulum. Significant amounts of a putative Golgi membrane marker are present in this fraction. The relatively high specific activities of Na+,K+-ATPase, 5'-nucleotidase, and [3H]fucose indicate that the fraction is enriched in surface membrane. Further purification of the fraction by equilibrium centrifugation on shallow sucrose gradients reduces further the contaminating activities and results in a PA distribution that closely parallels the distribution of the membrane enzyme, 5'-nucleotidase. PA was not released from its membrane association by hypotonic and hypertonic extraction and ultrasonication, while granule-bound enzymes were released by these treatments. The PA activity from hamster SV40 cells fractionated the same way as that of RSV-CEF. These results suggest that a protease that is dramatically enhanced upon malignant transformation is associated with "plasma membrane-like" elements of the cell and may serve as an intrinsic modifier of cell surface proteins after malignant transformation.
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PMID:Association of a protease (plasminogen activator) with a specific membrane fraction isolated from transformed cells. 99 59

A bile canalicular membrane fraction was isolated from 24-hour regenerating rat livers, and its properties were compared to those of homologous fractions prepared from the livers of sham-operated and unoperated controls. These canalicular membrane fractions were found to be closely related in terms of their morphology, their purity, their yield, and their qualitative protein banding profiles on sodium dodecyl sulfate-polyacrylamide gels. However, when a rigorous examination of plasma membrane enzyme marker activities was made, the regenerating liver membranes were shown to possess an increased specific activity of alkaline phosphatase and lower levels of Mg2+ ATPase and 5'-nucleotidase in comparison with control specific activity values.
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PMID:Isolation and partial characterization of a bile canalicular plasma membrane fraction from normal and regenerating rat liver. 115 69

A rapid small-scale procedure was set up to obtain highly purified preparations of lysosomes and plasma membranes from the homogenate of cerebellar granule cells differentiated in culture. It consisted in a centrifugation of the postnuclear fraction P2, on a Percoll gradient with formation of an upper and lower band. The upper band, upon centrifugation on 1 M sucrose, produced a light band lying on the top, that constituted the plasma membrane preparation. The upper band constituted the lysosome preparation. The plasma membrane preparation exhibited a 6-fold relative specific activity increase of Na+, K(+)-ATPase and 5'-nucleotidase, with negligible contamination by other subcellular markers; the lysosomal preparation exhibited a 30-fold relative specific activity increase of beta-galactosidase and beta-hexosaminidase, with virtually no contamination by other subcellular markers. Both the lysosome and plasma membrane preparations carried sialidase activity on MUB-NeuNAc and ganglioside GD1a. The sialidase activity on GD1a required the presence of Triton X-100 in both subcellular preparations; the sialidase activity on MUB-NeuNAc was markedly activated by albumin only in the lysosomes. The lysosomal sialidase had a unique optimal pH value, 3.9. The plasma membrane sialidase featured two values of optimal pH, one at 3.9, for both substrates and second at 5.4 and 6.0 for MUB-NeuNAc and GD1a, respectively. It is concluded that cerebellar granule cells differentiated in vitro possess one lysosomal sialidase and two plasma membrane sialidases, all of them active on ganglioside.
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PMID:Dual subcellular localization of sialidase in cultured granule cells differentiated in culture. 130 62

Renal epithelial function, proton flux and sodium stimulated proton flux, was observed in vesicles isolated from the brush border of the proximal tubule of Sockeye Salmon (Oncorhynchus nerka) during migration. Brush border membrane vesicles (BBMV) were isolated from the body kidney of Sockeye Salmon using aggregation/differential centrifugation techniques. Vesicle purity was tested using a series of epithelial and basal lateral markers including alkaline phosphatase, maltase, gamma-glutamyl transferase (GGTP), Mg(2+)-activated ATP-ase, Na(+)+K(+)-activated ATPase, and 5'-nucleotidase and the lysosomal marker acid phosphatase. An enrichment/depletion factor for each marker was determined by comparison of purified BBMV with kidney homogenate. Vesicles exhibit an enrichment factor for alkaline phosphatase, GGTP, maltase, Mg(2+)-activated ATP-ase, Na(+)+K(+)-activated ATPase, and 5'-nucleotidase. A depletion factor was observed for acid phosphatase. Vesicle integrity was tested by measuring the time course of proton flux in the presence of a pH gradient. Amiloride sensitive sodium stimulated proton flux was observed in these vesicles. The presence of sodium caused a saturable increase in the rate of proton flux, indicating the activity of a sodium/proton antiport protein in BBMV.
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PMID:Proton transport and Na+/H+ exchange in vesicles isolated from sockeye salmon (Oncorhynchus nerka) kidneys during migration from salt to fresh water. 132 4


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