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)

Man-mouse and man-Syrian hamster somatic hybrid cell lines were prepared by fusion of mouse A9 or hamster TG2 cells, which are deficient in hypoxanthine-guanine phosphoribosyl transferase, with cells of a diploid fibroblastic strain, KOP-1, derived from a woman heterozygous for an X-autosome translocation. 61 clones were derived in nonselective medium and 85 sublines of these were derived in selective media: 53 in hypoxanthine-aminopterine-thymidine and 32 in 8-azaguanine. All three human X-linked markers studied, i.e., hypoxanthineguanine phosphoribosyl transferase (EC 2.4.2.8), glucose-6-phosphate dehydrogenase (EC 1.1.1.49), and phosphoglycerate kinase (EC 2.7.2.3), were present together, or absent together, in most of these clones and sublines. However, loss or retention of only phosphoglycerate kinase was occasionally observed, even in the absence of selective growth, while no evidence of separation of hypoxanthine-guanine phosphoribosyl transferase from glucose-6-phosphate dehydrogenase occurred. Cytological examination of eight man-hamster clonal lines by the quinacrine fluorescent technique showed that human phosphoglycerate kinase was only present when the translocation chromosome carrying most of the long arm of the X chromosome was present. The presence of human glucose-6-phosphate dehydrogenase and hypoxanthine-guanine phosphoribosyl transferase was not related to the presence or absence of this chromosome, but appeared to be correlated with the presence of the other translocation chromosome.
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PMID:Cytological mapping of human X-linked genes by use of somatic cell hybrids involving an X-autosome translocation (mouse-hamster-human X-linked markers). 450 May 56

A hybrid cell line of clonal origin has been obtained by cocultivation of two biochemically marked human cell strains. One parental line is diploid and derived from a male infant with orotic aciduria, a rare autosomal recessive disease. This line has deficient activity for the final two enzymes in the biosynthetic pathway leading to uridylic acid and possesses the B electrophoretic type of glucose-6-phosphate dehydrogenase. The other parental line (D98/AH-2) is heteroploid, is resistant to 8-azahypoxanthine, and has deficient inosinic acid pyrophosphorylase activity. It displays the A(+) variant of glucose-6-phosphate dehydrogenase. The A(+) and B types of this dehydrogenase are known to be determined by allelic, sex-linked, Mendelian genes. The cloned hybrid cells exhibit genetic traits of both parents: (1) Their modal chromosome number is approximately the sum of those of the two parental lines; (2) they have levels of activity for both enzymes affected by the gene for orotic aciduria which are intermediate between those of the two parental lines; (3) they have higher activity than the D98/AH parent for inosinic acid pyrophosphorylase; (4) they have both A(+) and B isozyme bands of glucose-6-phosphate dehydrogenase. These hybrid cells represent the first known example of a cloned line of mammalian origin in which two X-linked allelic genes function.
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PMID:Hybridization of two biochemically marked human cell lines. 525 9

SIX INTERSPECIFIC SOMATIC HYBRID CELL LINES WERE DERIVED FROM A MOUSE LINE DEFICIENT IN HYPOXANTHINE: guanine phosphoribosyltransferase (HGPRT) and human diploid cells with normal enzyme activity. Human HGPRT was present in all six hybrids and the clones derived from them. However, in two of the six, and in some clones from another two, human glucose-6-phosphate dehydrogenase (G6PD) was absent. Since the structural loci for both these enzymes are X-linked in man, these findings suggest that these two loci have separated quite frequently through chromosome breakage and that they must be rather far apart on the X chromosome.
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PMID:Mitotic separation of two human X-linked genes in man--mouse somatic cell hybrids. 527 81

Expression of the two X-linked loci glucose-6-phosphate dehydrogenase (G6PD; EC 1.1.1.49) and hypoxanthine:guanine phosphoribosyltransferase (HGPRT; EC 2.4.2.8) was studied in single hair follicles of two females who were heterozygous for both of these genes (double heterozygotes). The coupling phase for these two loci was known to be g6pd A and hyprt(-) on the maternal X chromosome and g6pd B and hgprt(+) on the paternal X. Three phenotypic classes of hair follicles were observed in both double heterozygotes: G6pd A follicles with deficient HGPRT activity, G6pd B follicles with normal HGPRT activity, and G6pd AB follicles with intermediate HGPRT activity. These data directly demonstrate one of the predictions of the Lyon hypothesis that for two X-linked loci, those genes in cis position are turned on or off in a cell and its clone, while in trans only one gene or the other is expressed.
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PMID:Expression of two X-linked genes in human hair follicles of double heterozygotes. 528 30

A mouse-human somatic cell hybrid clone, deficient in hypoxanthine-guanine phosphoribosyltransferase (HPRT) and containing a structurally normal inactive human X chromosome, was isolated. The hybrid cells were treated with 5-azacytidine and tested for the reactivation and expression of human X-linked genes. The frequency of HPRT-positives clones after 5-azacytidine treatment was 1000-fold greater than that observed in untreated hybrid cells. Fourteen independent HPRT-positive clones were isolated and analyzed for the expression of human X markers. Isoelectric focusing showed that the HPRT expressed in these clones is human. One of the 14 clones expressed human glucose-6-phosphate dehydrogenase and another expressed human phosphoglycerate kinase. Since 5-azacytidine treatment results in hypomethylation of DNA, DNA methylation may be a mechanism of human X chromosome inactivation.
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PMID:Reactivation of an inactive human X chromosome: evidence for X inactivation by DNA methylation. 616 95

A mouse-human cell hybrid clone retaining an inactive human X chromosome was treated with 5-azacytidine. Following treatment, expression of the X-linked enzyme markers, hypoxanthine-guanine phosphoribosyltransferase (HPRT), glucose-6-phosphate dehydrogenase (G6PD), phosphoglycerate kinase (PGK), and alpha-galactosidase A (GLA) was examined. Results presented here show that 45 of the 62 clones positive for human HPRT expressed human GLA, while only four of 68 clones negative for human HPRT expressed human GLA. These results strongly suggest that there is coordinate reactivation of GLA and HPRT. Reactivated expression of G6PD was studied in detail. The studies show that 5-azacytidine can induce heritable changes in the inactive human X chromosome resulting in the expression of G6PD activity at a level lower than that from an active human X chromosome.
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PMID:Frequency of reactivation and variability in expression of X-linked enzyme loci. 620 21

Bovine embryonic trachea cells were hybridized with mouse A9 cells deficient in hypoxanthine phosphoribosyltransferase, and cattle-mouse hybrid cells clones were isolated after HAT/ouabain selection. In these interspecific cell hybrids, bovine glucose-6-phosphate dehydrogenase, alpha-galactosidase, and phosphoglycerate kinase were expressed concordantly with bovine HPRT. Their expression depended on the presence of bovine X chromosome. These data indicated that the genes for G6PD, PGK, and HPRT are linked and can be assigned to the bovine X chromosome.
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PMID:The bovine genes for phosphoglycerate kinase, glucose-6-phosphate dehydrogenase, alpha-galactosidase, and hypoxanthine phosphoribosyltransferase are linked to the X chromosome in cattle-mouse cell hybrids. 625 51

Pig--mouse somatic cell hybrids were obtained from fusion of HPRT--mouse cells (RAG) and pig lymphocytes. The pig-mouse hybrids examined apparently retained on the average only 9 to 15 pig chromosomes. Seven of the hybrid clones were karyotyped to determine the pig chromosome constitution, and the same hybrid clones were tested electrophoretically for the expression of pig hypoxanthine-guanine phosphoribosyltransferase (HPRT), glucose-6-phosphate dehydrogenase (G6PD), and alpha-galactosidase (alpha-GAL) phenotypes. All five of the hybrid clones which had retained the pig X-chromosome exhibited concordant expression of pig HPRT, G6PD, and alpha-GAL enzymes. These data indicate that the genes HPRT, G6PD, and alpha-GAL are located on the X-chromosome of the domestic pig.
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PMID:The localization of genes for HPRT, G6PD, and alpha-GAL onto the X-chromosome of domestic pig (Sus scrofa domesticus). 630 43

We have used a cloned cDNA for hypoxanthine-guanine phosphoribosyltransferase (HGPRT) to analyze the HGPRT gene and mRNA in an HGPRT-deficient mutant of Chinese hamster cells (RJK10) and its HGPRT-positive revertants. By Southern blot analysis, no DNA rearrangements were detected within the genes from any of the cell lines examined. However, four of five spontaneous revertants each contained 10- to 20-fold more copies of the HGPRT gene than did RJK10 or wild-type cells. In contrast, the gene was not amplified in four mutagen-induced revertants. The RJK10 mutation did not alter the size or concentration of HGPRT mRNA and representatives of the revertants contained the mRNA in amounts proportional to the number of genes they carried. Examples of clones with either stable or unstable gene amplification were identified and their HGPRT-positive phenotypes were shown to be dependent on the gene amplification. In a stably amplified revertant, the extra genes were found to be syntenic with the X chromosome marker glucose-6-phosphate dehydrogenase. In an unstable revertant only one of the 10 to 20 copies of the gene could be shown to be X linked. Thus, we found that RJK10 can revert by at least two distinct mechanisms: amplification of the HGPRT gene, which occurred spontaneously, or point mutation, which predominated after exposure to mutagens.
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PMID:Amplification versus mutation as a mechanism for reversion of an HGPRT mutation. 658 54

We report a unique and complex karyotypic rearrangement involving chromosomes X, 3, 7, and 21. Blood cells and fibroblasts from the proband do not express the maternal allele for glucose-6-phosphate dehydrogenase (G6PD), providing biochemical evidence for nonrandom expression of X-linked genes in balanced X-autosome translocations. The break point on the X chromosome, at the junction of Xq27-Xq28, separates the loci for hypoxanthine phosphoribosyltransferase (HPRT) and G6PD. Studies of mouse-human hybrids derived from the proband's cells indicate that G6PD, at q28, is clearly distal to all other X loci now assigned. From these and previous studies, we can localize HPRT to that segment between Xq26 and Xq27. The studies also provide further evidence for the stability of the inactive X phenotype in hybrid cells.
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PMID:Localization of loci for hypoxanthine phosphoribosyltransferase and glucose-6-phosphate dehydrogenase and biochemical evidence of nonrandom X chromosome expression from studies of a human X-autosome translocation. 693 Jun 69


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