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.
 ...
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.
 ...
PMID:Localized Derepression on the Human Inactive X Chromosone in Mouse-Human Cell Hybrids. 105 21

Permanent transfer of genetic information from chromosomes isolated from human diploid cells to recipient cells has been demonstrated. Human metaphase chromosomes were incubated with mouse A9 fibroblasts deficient in hypoxanthine phosphoribosyltransferase (IMP:pyrophosphate phosphoribosyltransferase, EC 2.4.2.8) and adenine phosphoribosyltransferase (AMP:pyrophosphate phosphoribosyltransferase, EC 2.4.2.7). Colonies of cells containing hypoxanthine phosphoribosyltransferase appeared during growth in a selective medium. The hypoxanthine phosphoribosyltransferase gene product in four independent colonies was identified as human donor species by both gel electrophoresis and isoelectric focusing; hence these colonies did not result from reversion of ta9 parental cells. Other X-linked human genes, glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NAD(+) 1-oxidoreductase, EC 1.1.1.49) and phosphoglycerate kinase (ATP:3-phospho-D-glycerate 1-phosphotransferase, EC 2.7.2.3), were not expressed in these same colonies. Dissociation of expression of these X-linked genes probably results from chromosomal fragmentation during uptake, but other mechanisms have not been excluded.
 ...
PMID:Human gene expression in rodent cells after uptake of isolated metaphase chromosomes. 105 70

We have analysed the recovery of individual CHO-derived mutants during the generations immediately following their induction. This characteristic, which we call persistence, was measured by propagating mutagenized cultures in non-selective medium after subdivision into many very small populations, each containing either zero or one mutant. The recovery of most hypoxanthine phosphoribosyltransferase (hprt)-deficient mutants induced by ethyl methanesulphonate was low, and we have previously shown that this was usually due to an apparent rapid loss of the mutant phenotype with continued culture in non-selective medium (Bradley, 1980). A minority of about 15% manifest high persistence. We now show that most adenine phosphoribosyltransferase (aprt)-deficient mutants and some ouabain-resistant mutants had low persistence. Mutants induced by UV irradiation also generally exhibited low persistence but those induced by X-irradiation had significantly higher persistence than what was seen among EMS-induced mutants. Among various sublines of CHO cells which were tested for persistence of induced mutants, only one group consistently yielded mutants of high persistence. These were lines which carried glucose-6-phosphate dehydrogenase mutations which themselves had been originally induced by EMS.
 ...
PMID:Low persistence of the induced mutant phenotype in Chinese hamster cells. 253 33

Six mutations, impairing DNA polymerase of E. coli in combination with the wild type gene for rho factor or ts-mutation rho 15 have been studied in relation to the expression of seven operons having different types of regulation. The expression of genes for glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase is shown to be constitutive and resistant to mutationally altered RNA polymerase and rho factor. The expression of genes for adenine phosphoribosyltransferase and of deo operon is regulated by rho dependent attenuators with attenuation being lifted incomplete medium. Mutation rho 15 decreases the level of enzymes of thr and lac operons independent of mRNA levels of these operons. Mutation rho 15 effect on posttranscriptional level is modified by mutations damaging RNA polymerase. The data obtained suppose RNA polymerase to affect all stages of realization of genetic information, beginning with promoter recognition and RNA synthesis and including the protein synthesis on mRNA.
 ...
PMID:[Effect of mutation changes in RNA-polymerase and transcription termination factor rho on expression of various operons in E. coli]. 302 82