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)

The subcellular origin of membranes from rat skeletal muscle that contain insulin-responsive glucose transporters was investigated. Rat skeletal muscle membranes were prepared by isopycnic centrifugation in sucrose gradients. In vivo insulin treatment increased the content of GLUT-4 glucose transporters in the 25% sucrose fraction (enriched in the plasma membrane marker 5'-nucleotidase) and decreased it in the 35% sucrose fraction (devoid of plasma membrane markers). The possibility of endothelial cell membrane contamination in these fractions was investigated using a mouse monoclonal antibody, MRC OX-43, raised against a cell surface protein specific to rat vascular endothelium. MRC OX-43 did not react with any of the muscle membrane fractions, but did recognize a protein of around 100 kDa in extracts of human endothelial cells and rat aorta. An antibody to the dihydropyridine receptor of skeletal muscle, IIC12, was used to determine the presence of transverse tubules in these fractions. IIC12 reacted positively with a 180-kDa protein in purified rat transverse tubules. In contrast, this antibody did not cross-react with the 25% or 35% sucrose fractions. The 25% sucrose fraction was devoid of calsequestrin and ryanodine receptor, cisternal sarcoplasmic reticulum markers. However, small amounts of these proteins were detected in the 35% sucrose fraction. The results suggest that the 25% sucrose fraction represents plasma membranes, while the 35% sucrose fraction is an insulin-sensitive intracellular fraction that contains, but is not enriched in, sarcoplasmic reticulum cisternae. The results further show that insulin-induced recruitment of GLUT-4 transporters in skeletal muscles can be demonstrated independently of GLUT-4 recruitment in endothelial cells.
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PMID:Characterization of glucose transporter-enriched membranes from rat skeletal muscle: assessment of endothelial cell contamination and presence of sarcoplasmic reticulum and transverse tubules. 198 44

We have previously assigned human ecto-5'-nucleotidase (NT) to chromosome 6 on the basis of conversion of exogenously supplied [14C]AMP to adenosine by whole cells of human and Chinese hamster hybrids carrying chromosome 6. In this paper we demonstrate that the activity on human MRC-5 fibroblasts is typical of previously described and purified ecto-5'-nucleotidases. In contrast to MRC-5 cells, Chinese hamster V79A2 cells weakly express an AMPase activity that is not NT. The cytosolic form of NT in human and hybrid fibroblasts is similar to the ectoenzyme in substrate specificity. Hybrids that lack chromosome 6 express neither the ecto- nor the cytosolic enzyme, suggesting that both forms may be coded by the same gene on chromosome 6. Ecto-ATPase, ecto-ADPase, and ecto-ADP kinase activities are each expressed at similar levels in MRC-5 and V79A2. The ATPase, ADPase and NT activities of MRC-5 cells act sequentially to generate adenosine. A similar cascade acts on V79A2 cells but the lack of NT causes the accumulation of AMP.
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PMID:Nucleotide ectoenzyme activities of human and Chinese hamster fibroblasts in tissue culture. 256 Jun 29

The carbocyclic analog of 2'-deoxyguanosine (CdG) has broad-spectrum antiviral activity. Because of recent observations with other nucleoside analogs that biological activity may be associated the L enantiomer rather than, as expected, with the D enantiomer, we have studied the metabolism of both enantiomers of CdG to identify the enzymes responsible for the phosphorylation of CdG in noninfected and virally infected human and duck cells. We have examined the enantiomers as substrates for each of the cellular enzymes known to catalyze phosphorylation of deoxyguanosine. Both enantiomers of CdG were substrates for deoxycytidine kinase (EC 2.7.1.74) from MOLT-4 cells, 5'-nucleotidase (EC 3.1.3.5) from HEp-2 cells, and mitochondrial deoxyguanosine kinase (EC 2.7.1.113) from human platelets and CEM cells. For both deoxycytidine kinase and mitochondrial deoxyguanosine kinase, the L enantiomer was the better substrate. Even though the D enantiomer was the preferred substrate with 5'-nucleotidase, the rate of phosphorylation of the L enantiomer was substantial. The phosphorylation of D-CdG in MRC-5 cells was greatly stimulated by infection with human cytomegalovirus. The fact that the phosphorylation of D-CdG was stimulated by mycophenolic acid and was not affected by deoxycytidine suggested that 5'-nucleotidase was the enzyme primarily responsible for its metabolism in virally infected cells. D-CdG was extensively phosphorylated in duck hepatocytes, and its phosphorylation was not affected by infection with duck hepatitis B virus. These results are of importance in understanding the mode of action of D-CdG and related analogs and in the design of new biologically active analogs.
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PMID:Metabolism in human cells of the D and L enantiomers of the carbocyclic analog of 2'-deoxyguanosine: substrate activity with deoxycytidine kinase, mitochondrial deoxyguanosine kinase, and 5'-nucleotidase. 959 24