Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.2.8 (hypoxanthine-guanine phosphoribosyltransferase)
 2,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

5-Phosphoribosyl 1-pyrophosphate synthetase (PRibPP synthetase EC 2.7.6.1) isolated from rat intestinal mucosa was found to be membrane associated. The subcellular distribution of PRibPP synthetase activity seems to parallel that of gamma-glutamyl transpeptidase, indicating it to be in the brush border. The tip cells of rat intestinal mucosa were richer in PRibPP synthetase than the crypt cells. Chromatography of a Triton-solubilized particulate fraction unmasked a peak of hypoxanthine phosphoribosyltransferase activity that was not detectable before. The activity, too, was concentrated in the brush border. The coexistence of these two activities in the fraction of the bowl involved in absorption has led to the suggestin that the synthetase and phosphoribosyl-transferase are part of a coupled transport system.
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PMID:Subcellular distribution of PRibPP synthetase activity of rat intestinal mucosa. 625 88

Sealed and unsealed plasma membrane vesicles were prepared from human erythrocytes and lymphocytes. Phosphoribosylpyrophosphate synthetase (PRibPP synthetase), hypoxanthine phosphoribosyltransferase (HPRTase), and adenine phosphoribosyltransferase (APRTase) activities are detectable on both inside-out and right-side-out sealed vesicles. Ghost preparations were about 0.2%, 1%, and 1.2% of the total erythrocyte and 0.5%, 5.3%, and 9.7% of the lymphocyte APRTase, HPRTase, and PRibPP synthetase activities. The rapid decrease in these enzyme activities, upon further purification of the membranes, seemed to suggest that they might be loosely bound extrinsic proteins. Evidence confirming the localization of these enzymes on the cell surface was obtained by measuring production of [14C]AMP by intact cells in medium containing [14C]adenine, ribose 5-phosphate, and Mg2+ATP. The formation of AMP was linear with time and number of cells present. Magnesium and phosphate exerted different effects on the production of extracellular AMP than on intracellular, which involves transport as well as phosphoribosylation. Cytosoluble and membrane-bound APRTase and PRibPP synthetase exhibited different catalytic properties and sensitivities to effectors. Membranes of erythrocytes of HPRTase-deficient patients contain little or no HPRTase activity when assayed in the absence of Triton. Reisolation of these membranes from admixture with normal hemolysates did not result in any bound activity; thus, the membrane-bound activity is not an artifact of the isolation procedure. Lysis with Triton released activity equal to about half that of control membranes. This is further evidence that the enzyme is firmly bound to the membrane.
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PMID:Membrane-associated purine metabolizing enzyme activities of human peripheral blood cells. 629 41

The toxicity and mutagenicity of aqueous and organic extracts of soil contaminated with TNT, TNT metabolites and hexogen was determined in mammalian cell lines and in prokaryotic cells. The prokaryotic toxicity was determined via the colony forming ability of Salmonella typhimurium (strains TA 98 and TA 100). The same strains were used to test mutagenicity in the Ames test. The mammalian toxicity was analyzed in human fibroblasts by the inhibition of cell growth and cell viability (MTT assay). The mammalian mutagenicity was tested with the HPRT test in V79 cells (hamster lung). The aqueous soil extract did not reveal toxicity or mutagenicity in any of the tests performed. The DMSO/ethanol extract showed toxicity and mutagenicity in S. typhimurium. Thereby strain TA 98 was more sensitive than strain TA 100. In human fibroblasts cell growth was strongly inhibited, whereas no reduction of cell viability was found in the MTT test. Mutagenicity of the DMSO/ethanol extract of the soil was demonstrated in V79 cells.
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PMID:Cytotoxicity and mutagenicity of a 2,4,6-trinitrotoluene (TNT) and hexogen contaminated soil in S. typhimurium and mammalian cells. 965 Feb 64