Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00492 (hypoxanthine-guanine phosphoribosyltransferase)
 2,385 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

Trinitrotoluene (TNT) and related compounds were tested for induction of mutation in the CHO-hprt mutation assay. The parent compound, TNT, was consistently found to be mutagenic at concentrations above 40 microg ml(-1), whether or not S9 activating enzymes were added. Five TNT metabolites gave statistically significant but small increases in mutation frequency over solvent controls: 4-amino-2,6 dinitrotoluene, 2,4',6,6'-tetranitro-2',4-azoxytoluene, 2,2',6,6'-tetranitro-4,4'-azoxytoluene, 2',4,6,6'-tetranitro-2,4'-azoxytoluene and triaminotoluene. Clear dose-response relationships could not be established for the mutagenic response of these compounds. They are considered as very weak mutagens in this mammalian test system. Five compounds did not produce statistically significant mutation frequencies at the levels tested: 2-amino-4,6-dinitrotoluene, 2,4-diamino-6-nitrotoluene, 1,3,5-trinitrobenzene, 2,6-diamino-4-nitrotoluene and 4,4',6,6'-tetranitro-2,2'-azoxytoluene. The results indicate that none of the TNT metabolites tested pose a significant mutational health risk, at least as judged by the CHO-hprt assay.
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PMID:Mutation analyses of a series of TNT-related compounds using the CHO-hprt assay. 1118 Feb 65