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)

Nuclei, nuclear membranes and rough endoplasmic reticulum (rER) were isolated from onion root tips and stems. Structural preservation and purity of the fractions was determined by electron microscopic and biochemical methods. Gross compositional data (protein, phospholipid, nonpolar lipids, sterols, RNA, DNA), phospholipid and fatty acid patterns, enzyme activities (ATPases, ADPase, IDPase, glucose-6-phosphatase, 5'-nucleotidase, acid phosphatase, and NADH- and NADPH-cytochrome C reductases), and cytochrome contents were determined. A stable, high salt-resistant attachment of some DNA with the nuclear membrane was observed as well as the association of some RNA with high salt-treated nuclear and rER membranes. The phospholipid pattern was identical for both nuclear and rER membranes and showed a predominance of lecithin (about 60%) and phosphatidyl ethanolamine (20-24%). Special care was necessary to minimize lipid degradation by phospholipases during isolations. Nonpolar lipids, mostly sterols and triglycerides, accounted for 35-45% of the membrane lipids. Sterol contents were relatively high in both membrane fractions (molar ratios of sterols to phospholipids ranged from 0.12 to 0.43). Sitosterol accounted for about 80% of the total sterols. Palmitic, oleic, and linoleic acids were the most prevalent acids in membrane-bound lipids as well as in storage lipids and occurred in similar proportions in phospholipids, triglycerides and free fatty acids of the membrane. About 80% of the fatty acids in membrane phospholipids and triglycerides were unsaturated. A cytochrome of the b5 type was characterized in these membranes, but P-450-like cytochromes could not be detected. Both NADH and NADPH-cytochrome c reductases were found in nuclear and rER membranes and appeared to be enriched in rER membranes. Among the phosphatases, Mg2+-ATPase and, to lesser extents, ADPase, IDPase and acid phosphatase activities occurred in the fractions, but significant amounts of monovalent ion-stimulated ATPase, 5'-nucleotidase and glucose-6-phosphatase activities did not. The results obtained emphasize that the close biochemical similarities noted between rER and nuclear membranes of animal cells extend to these fractions from plant cells.
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PMID:Characterization of nuclear membranes and endoplasmic reticulum isolated from plant tissue. 17 22

A Golgi apparatus-rich fraction and a plasma membrane-rich fraction were isolated from a common homogenate of rat liver. Their respective buovant densities, appearances in the electron microscope and 5'-nucleotidase and UDP-galactose ovalbumin galactosyltransferase activities were in accord with published data on separately isolated Golgi apparatus-rich and plasma membrane-rich fractions. Contamination by endoplasmic reticulum and mitochondria was low. Gel electrophoresis of the membrane proteins of the Golgi apparatus-rich and plasma membrane-rich fractions (separately and mixed) showed a close similarity. After Neville's demonstration that electrophoretic patterns of membrane protein subunits from different subcellular fractions are easily distinguishable, the present work demonstrates an unusually close relationship between the Golgi apparatus membrane and the cell membrane. It is possible that membrane similarity may be mediated by the transfer of membrane-bound vesicles from the Golgi apparatus to the cell membrane.
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PMID:Similarities of the Golgi apparatus membrane and the plasma membrane in rat liver cells. 17 74

The subcellular distribution of adenyl cyclase was investigated in small intestinal epithelial cells. Enterocytes were isolated, disrupted and the resulting membranes fractionated by differential and sucrose gradient centrifugation. Separation of luminal (brush border) and contra-luminal (basolateral) plasma membrane was achieved on a discontinuous sucrose gradient. The activity of adenyl cyclase was followed during fractionation in relation to other enzymes, notably those considered as markers for luminal and contraluminal plasma membrane. The luminal membrane was identified by the membrane-bound enzymes sucrase and alkaline phosphatase and the basolateral region by (Na+ + K+)-ATPase. Enrichment of the former two enzymes in purified luminal plasma membrane was 8-fold over cells and that of (Na+ + K+)-ATPase in purified bisolateral plasma membranes was 13-fold. F--activated adenyl cyclase co-purified with (Na+ + K+)-ATPase, suggesting a common localization on the plasma membrane. The distribution of K+-stimulated phosphatase and 5'-nucleotidase also followed (Na+ + K+)-ATPase during fractionation.
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PMID:The surface membrane of the small intestinal epithelial cell. I. Localization of adenyl cyclase. 17 91

A model is proposed for the partial depletion of the adenine nucleotide pool in the ischemic perfused rat heart which involves seven enzymes: adenylate cyclase, 3',5'-cyclic AMP phosphodiesterase, 5'-nucleotidase, adenosine kinase, adenosine deaminase, purine nucleoside phosphorylase, and inorganic pyrophosphatase. The computer implementation of this model is in terms of rate laws, several of which were obtained by a systematic least-squares fitting procedure. Depletion of the adenine nucleotide pool is initiated by the release of endogenous noradrenaline into the interstitial fluid, which results from a fall in tissue PO2, and the subsequent activation of adenylate cyclase. In this model the substrate for 5'-nucleotidase is a membrane-bound AMP pool formed by hydrolysis of extracellular fluid and functions as a vasodilator; excess adenosine is incorporated into the tissue by a "permease" with Michaelis-Menten kinetics and converted to AMP, inosine, and hypoxanthine. Alternative mechanisms, such as the deamination of AMP by adenylate deaminase and conversion of AMP to adenine by AMP pyrophosphorylase, were rejected primarily on qualitative biochemical grounds.
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PMID:Computer simulation of ischemic rat heart purine metabolism. I. Model construction. 19 89

The UHF fraction from NIL 8 hamster embryo fibroblasts contains the LETS protein and several other major proteins. It exhibits three enzymatic activities in significant amounts: 5'-nucleotidase, alkaline phosphatase, and galactosyl transferase. The latter two appear to be different from the membrane-bound enzymes. This fraction is heavily stained with ruthenium red, a dye specific for the cell coat in intact cells. A comparable fraction from hamster sarcoma virus-transformed cells exhibits a similar overall protein composition but lacks at least three major proteins, including the LETS protein. Compared to NIL 8 cells, the distribution of alkaline phosphatase in fractions from these cells is different, and the level of galactosyl transferase in the UHF is much reduced.
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PMID:Cell surface coat of hamster fibroblasts. 29 62

1. Free and membrane-bound mouse liver polyribosomes were separated by prolonged density-gradient centrifugation of the post-mitochondrial supernatant. RNA was extracted from free and membrane-bound polyribosomes and mRNA purified by oligo(dT)-cellulose column chromatography. 2. Antisera against purified mouse liver plasma membrane 5'-nucleotidase and moust albumin were prepared and characterized. 3. Microinjection of equivalent amounts of mRNA from free and membrane-bound liver polyribosomes into Xenopus laevis oocytes indicated by immuno precipitation and sodium dodecylsulphate gel electrophoresis a higher proportion of mRNA coding for 5'-nucleotidase and serum albumin in membrane-bound polyribosomes than free polyribosomes. 4. Although small, significant amounts of serum albumin and 5'-nucleotidase were also coded for by mRNA purified from free polyribosomes. The results suggest that in vivo, mRNA in mouse liver membrane-bound polyribosomes codes for the synthesis of 17 times more 5'-nucleotidase than does the mRNA in free polyribosomes.
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PMID:Biogenesis of plasmalemmal glycoproteins. Intracellular site of synthesis of mouse liver plasmalemmal 5'-nucleotidase as determined by the sub-cellular location of messenger RNA coding for 5'-nucleotidase. 81 Jun 23

Electrophoretic patterns of polypeptides of milk fat globule differed quantitatively depending on extent of washing during membrane preparation. This was due to selective loss of loosely associated, extrinsic membrane proteins. Major polypeptides with apparent molecular weights of 155,000 and 43,500 and membrane glycoproteins were released selectively during preparation of milk fat globule membranes. Evidence suggested that xanthine oxidase was a constituent of the selectively removed polypeptide fraction of apparent molecular weight 155,000. A major class of polypeptide with an apparent molecular weight of 62,500 was not extracted from milk fat globule membrane by treatment with dilute salts, ethylenediaminetetraacetic acid, or by nonionic and ionic detergent solutions. Milk fat globule membranes were separated into seven subfractions on isopycnic centrifugation in sucrose density gradients. Specific activities of the enzymes 5'-nucleotidase, xanthine oxidase, acid and alkaline phosphatases were similar or identical in all fractions. Electrophoretic analysis showed these seven subfractions had similar polypeptide profiles. Both phospholipid and total lipid content of subfractions were correlated inversely with fraction density. The results show that milk fat globule membrane is nearly homogenous in content of intrinsic membrane proteins and certain membrane-bound enzyme activities but is markedly heterogeneous with respect to buoyant density and lipid content.
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PMID:Membranes of mammary gland. XII. Loosely associated proteins and compositional heterogeneity of bovine milk fat globule membrane. 84 88

The treatment of plasma membranes by a French pressure cell in sucrose medium devoid of detergents solubilized 20% of the total protein and 95--100% of 5'-nucleotidase activity. The soluble enzyme was 40--90-fold purified by centrifugation in a sucrose gradient with a 10--20% yield with respect to the orginal lysate. The purified fraction retained the same high specificity for 5'-AMP (Km = 20 micron) as in the plasma membranes and was enriched in sphingomyelin. Whereas 5'-AMP at high concentration inhibited the membrane-bound enzyme, it had no effect on the solubilized form. The soluble enzyme was stimulated by 2 X 10(-13)-2 X 10(-15) g concanavalin A without any inhibition with higher doses of lectin. The plasma-membrane bound stimulated and inhibited 5'-nucleotidase was modulated by concanavalin A concentrations higher than 0.1 microgram. Inhibition of the activity of the soluble enzyme by antiphosphorylcholine antibodies was not observed with membranes. The regulation of 5'-nucleotidase acitvity in plasma membranes might be associated with a supramolecular organization.
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PMID:Differences in the modulations of the soluble of plasma-membrane-bound 5'-nucleotidase. 92 72

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

Sodium butyrate causes HeLa cells to assume an elongated and jagged shape. Ultrastructurally this change is associated with the formation of bundles of microfilaments. Desmosomes were present between adjacent cells. No increase in microtubules was observed in the butyrate-treated cells. Butyrate induces an increase in the activity of 2 membrane-bound enzymes, alkaline phosphatase and 5'-nucleotidase; however, the activity of a third membrane enzyme, acetylcholine esterase, is reduced. The activities of the several other enzymes with different subcellular localizations are not significantly increased. Colcemid and cytochalasin B prevent or reverse the butyrate-mediated change in HeLa cell morphology and also partially inhibit the induction of alkaline phosphatase activity in these cells. The effect of cytochalasin B on alkaline phosphatase induction may be caused by a reduction in protein synthesis produced by this fungal metabolite.
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PMID:Ultrastructural and enzymic modulation of HeLa cells induced by sodium butyrate and the effects of cytochalasin B and colcemid. 97 76


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