Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.2.7 (adenine phosphoribosyltransferase)
 692 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mutants of Chinese hamster ovary cells deficient in glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP 1-oxidoreducatse, EC 1.1.1.49) activity were isolated after mutagenesis with ethyl methane sulfonate. The mutants were induced at frequencies of about 10-4 and do not differ in growth properties from wild-type cells. They were isolated by means of a sib selection technique coupled with a histochemical stain of colonies for enzyme activity. The lack of enzyme activity is not due to a dissociable inhibitor, and is recessive in hybrid cells. Multiple mutants that lack hypoxanthine phosphoribosyltransferase activity (IMP:pyrophosphate phosphoribosyltransferase, EC 2.4.2.8) and adenine phosphoribosyltransferase activity (AMP:pyrophosphate phosphoribosyltransferase, EC 2.4.2.7) were isolated by further mutagenesis. By following segregation of wild-type phenotypes from heterozygous multiply marked hybrid cells, it was shown that the genes responsible for glucose-6-phosphate dehydrogenase activity and hypoxanthine phosphoribosyltransferase activity are linked in Chinese hamster cells, in agreement with the location of both on the X chromosome in humans. No linkage to adenosine phosphoribosyltransferase was found. The isolation of mutant cells carrying linked markers should prove useful for studying chromosomal events such as segregation, breakage, recombination, and X-chromosome reactivation.
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PMID:Isolation of mammalian cell mutants deficient in glucose-6-phosphate dehydrogenase activity: linkage to hypoxanthine phosphoribosyl transferase. 105 32

Evidence for derepression of the gene for hypoxanthine phosphoribosyltransferase (HPRT; IMP: pyrophosphate phosphoribosyltransferase, EC 2.4.2.8) on the human inactive X chromosome was obtained in hybrids of mouse and human cells. The mouse cells lacked HPRT and were also deficient in adenine phosphoribosyltransferase (APRT; AMP: pyrophosphate phosphoribosyltransferase; EC2.4.2.7). The human female fibroblasts were HPRT-deficient as a consequence of a mutation on the active X but contained a normal HPRT gene on the inactive X. The two human X chromosomes were further distinguished by differences in morphology: the inactive X was morphologically normal while the active X included most of the long arm of autosome no. 1 translocated to the distal end of the X long arm. Forty-one hybrid clones were first isolated by selection for the presence of APRT; when these clones were selected for HPRT, six of them yielded derivatives having human HPRT with incidences of about 1 in 10-6 APRT-selected hybrid cells. The HPRT-positive derivatives contained a normal-appearing X chromosome indistinguishable from the inactive X of the parental human fibroblasts. The active X with the translocation was not found in any of the HPRT-positive hybrid cells. Human phosphoglycerokinase (ATP:3-phospho-D-glycerate 1-phosphotransferase. EC 2.7.2.3) and glucose-6-phosphate dehydrogenase (D-glucose 6-phosphate: NADP 1-oxidoreductase, EC 1.1.1.49), which are specified by X-chromosomal loci, were not detected in the hybrids expressing HPRT even though they contained an apparently intact X chromosome. The observations are most simply explained by the infrequent, stable derepression of inactive X chromosome segments that include the HPRT locus but not the phosphoglycerokinase and glucose-6-phosphate dehydrogenase loci.
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PMID:Localized Derepression on the Human Inactive X Chromosone in Mouse-Human Cell Hybrids. 105 21