Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

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

Somatic cell hybrid clones were derived from the fusion of hypoxanthine phosphoribosyltransferase (HPRT; EC 2.4.2.8)-deficient mouse cells and two different human fibroblast strains, each carrying an X chromosome-autosome translocation. One of these had an X/11 translocation [46,X,t(X;11)(p21;q13)] and the other had an X/19 translocation [46,X,t(X;19)(q22;q13)]. The structurally normal human X chromosome is the late-replicating (genetically inactive) chromosome in these two cell strains; the rearranged X chromosome is early replicating (genetically active). One primary hybrid clone carrying both the translocated X chromosome and the structurally normal X chromosome was isolated in hypoxanthine/aminopterin/thymidine medium from each of these two cell fusion experiments. These clones were then selected in medium containing 8-azaguanine to achieve the loss of the active human HPRT locus. Five subclones from the cell hybrid with the X/11 translocation failed to express two known human X-chromosome markers [glucose-6-phosphate dehydrogenase (G6PD; EC 1.1.1.49) and phosphoglycerate kinase (PGK; EC 2.7.2.3)] but did express human microsomal steroid sulfatase (STS; sterol-sulfate sulfohydrolase, EC 3.1.6.2). Three of these were cytogenetically analyzed and found to contain a structurally normal human X chromosome but not the X/11 translocation. Two subclones were isolated in 8-azaguanine from the hybrid with the X/19 translocation. Cytogenetic analysis of these two clones showed the presence of a structurally normal human X chromosome; the X/19 translocation was not present. They did not express human G6PD, PGK, or HPRT but did express human STS. These results indicate that human STS is expressed from a locus on the inactive human X chromosome and support our earlier finding that the STS locus escapes X-inactivation in man.
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PMID:Expression of an X-linked gene from an inactive human X chromosome in mouse-human hybrid cells: further evidence for the noninactivation of the steroid sulfatase locus in man. 693 82

Mouse A9 cells, L-cell-derived mutants deficient in hypoxanthine phosphoribosyltransferase (HPRT; IMP:pyrophosphate phosphoribosyltransferase, EC 2.4.2.8) were found to be incapable of binding (125)I-labeled epidermal growth factor (EGF) to the cell surface. The A9 cells were fused with human diploid fibroblasts (WI-38) possessing EGF-binding ability, and human-mouse cell hybrids (TA series) were isolated after hypoxanthine/aminopterin/thymidine/ouabain selection. Analyses of isozyme markers and chromosomes of four representative clones of TA hybrids indicated that the expression of EGF-binding ability is correlated with the presence of human chromosome 7 or 19. Four subclones were isolated from an EGF-binding-positive line, TA-4, and segregation of EGF-binding was found to be concordant with the expression of human mitochondrial malate dehydrogenase (MDHM; L-malate:NAD(+) oxidoreductase, EC 1.1.1.37), a marker for chromosome 7, but not with glucosephosphate isomerase (GPI; D-glucose-6-phosphate ketol-isomerase, EC 5.3.1.9), a marker for chromosome 19. Furthermore, evidence from 27 clones of AUG hybrids that were produced between A9 and another human fibroblast line, GM1696, carrying an X/7 chromosome translocation indicated that EGF-binding ability segregates together with human MDHM and two X-linked markers, HPRT and glucose-6-phosphate dehydrogenase (G6PD; D-glucose-6-phosphate:NADP(+) 1-oxidoreductase, EC 1.1.1.49), that are located on the translocation chromosome 7p(+). These results permit assignment of the gene, designated EGFS, which is associated with the expression of EGF-binding ability, to human chromosome 7 and its localization to the p22-qter region. Because the EGF receptor is reported to be a glycoprotein the EGFS could be either a structural gene(s) for receptor protein or a gene(s) for modifying the receptor protein through glycosylation.
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PMID:Genetics of cell surface receptors for bioactive polypeptides: binding of epidermal growth factor is associated with the presence of human chromosome 7 in human-mouse cell hybrids. 696 72

RJK39 is a clone of Chinese hamster cells carrying a mutation which inactivates hypoxanthine-guanine phosphoribosyltransferase (HGPRT) and reduces the apparent molecular weight of the enzyme. Using mutagens, we have isolated subclones of RJK39 which will grow in the counterselective HAT medium. Some continue to be HGPRT-deficient and survived the selection because they are resistant to aminopterin. In all but one of the HGPRT-positive revertants, the molecular weight of the enzyme returned to the wild-type value. However, the phenotypes of several of those strains indicate they produce altered forms of HGPRT, and one can conclude that second-site mutations must be able to cause intragenic suppression of the original mutation in RJK39. One of the revertants is pseudotetraploid and functionally heterozygous at the HGPRT locus. Segregation studies with that clone localized the genes for HGPRT, glucose-6-phosphate dehydrogenase, and phosphoglycerate kinase to the short arm of the Chinese hamster X chromosome.
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PMID:Reversion of a mutation affecting the molecular weight of HGPRT: intragenic suppression and localization of X-linked genes. 719 35

Inherited variations in monoamine oxidase (MAO) activity are thought to affect human behavior and expression of disease. The present study has established the chromosomal location of one of the structural genes coding for this enzyme. Mapping was carried out by somatic cell hybridization between normal human skin fibroblasts and mouse neuroblastoma cells. Selective media for growth of cells with or without hypoxanthine phosphoribosyltransferase (HPRT) activity were used to obtain hybrid lines which had retained or lost the human X chromosome, respectively. Cytogenetic techniques, isozyme analysis, and limited proteolysis and peptide mapping of [3H]pargyline-labeled MAO were used to characterize hybrid lines. With one exception, only lines containing the human X chromosome and human forms of two X-linked enzymes (phosphoglycerate kinase and glucose-6-phosphate dehydrogenase) expressed the human form of the flavin polypeptide of type A MAO. The exceptional hybrid line contained a putative translocation of part of the human X chromosome, since it expressed human forms of both MAO and phosphoglycerate kinase but neither the human form of glucose-6-phosphate dehydrogenase nor HPRT activity. This evidence indicates that the structural gene for the flavin polypeptide of MAO-A is on the human X chromosome. This represents the first chromosomal assignment of a human gene coding for an enzyme of neurotransmitter metabolism. This information will help to elucidate the structure of MAO and modes of its inheritance in the human population.
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PMID:Gene for monoamine oxidase type A assigned to the human X chromosome. 719 39

The subjects of this study were individuals with the form of X-linked mental retardation that is associated with the presence of a cytologically variant X chromosome having a secondary constriction or "fragile site" at Xq 27-28 (Fra X). Studies were carried out to test the hypothesis that deletions or modifications at neighboring loci occur as a consequence of events at the fragile site. Skin fibroblasts and peripheral blood lymphocytes from affected males were analyzed with respect to the expression of two X-lined enzymes: glucose-6-phosphate dehydrogenase (G6PD) and hypoxanthine phosphoribosyltransferase (HPRT); loci for these enzymes are known to be located in the region of the fragile site. Although the number of cells resistant to thioguanine (HPRT-deficient) obtained from some cultures from one Fra X male and blood cells of another was greater than expected, the frequency of these cells was not increased in cultures from other Fra X males. Furthermore, our results indicate that the G6PD activity and electrophoretic mobility in Fra X males is similar to that in normal cells, thus providing no evidence for the loss of the long-arm telomere in the fragile X syndrome.
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PMID:Fragile X syndrome: search for phenotypic manifestations at loci for hypoxanthine phosphoribosyltransferase and glucose-6-phosphate dehydrogenase. 729 24

To test whether chromosomal instability is associated with familial Alzheimer's disease, we examined breakage on X chromosomes of fibroblasts derived from patients with familial Alzheimer's disease, using gene cotransfer methodology. The X chromosome is a convenient target for analyzing DNA breakage because of its numerous markers and ease of selection in rodent-human hybrid cells. Patients with familial Alzheimer's disease, including the large Nova Scotia Alzheimer's kindred, show a significantly lower cotransfer of the X-linked glucose-6-phosphate dehydrogenase (G6PD) gene with the selected HPRT gene in hybrid cells, indicating breakage between the markers. Lower cotransfer of the more distant X-linked gene, MIC-2, was statistically significant in this kindred, but not in other patients with familial Alzheimer's disease. The distance between MIC2 and HPRT is sixfold to ninefold greater than that between HPRT and G6PD, suggesting that there may be a "hot spot" for breakage in the latter interval on the X chromosome of patients with familial Alzheimer's disease. The somatic cell hybrid model provides insights into underlying mechanisms for chromosomal breakage induced by the Alzheimer defect. A hypothesis implicating a candidate gene, C1-THF synthase, in the generation of chromosome instability in the pathogenesis of familial Alzheimer's disease, is presented.
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PMID:Chromosomal fragility associated with familial Alzheimer's disease. 805 55

To clarify the extent of cell lineage involvement in chronic myelogenous leukemia (CML), we investigated the bcr gene rearrangement and clonality using the X-chromosome-linked restriction fragment length polymorphism (RFLP) methylation method in T lymphocytes and granulocytes. We examined the granulocyte and T-cell fractions from the peripheral blood of seven female patients with CML during the chronic phase; patients were heterozygous for RFLPs at the phosphoglycerate kinase (PGK) or the hypoxanthine phosphoribosyltransferase (HPRT) gene. RFLP-methylation analysis of granulocytes demonstrated a monoclonal pattern in six of the seven patients and a rearranged bcr gene in all seven patients. In contrast, T lymphocytes exhibited a polyclonal pattern in six cases; in one case, a faint band was observed following methyl-sensitive enzyme cleavage. The bcr gene analysis in T lymphocytes showed the germline in every case. Our results indicate that the majority of T lymphocytes are polyclonal during the chronic phase of CML and confirm previous reports based on glucose-6-phosphate dehydrogenase, cytogenetic, and bcr rearrangement analyses.
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PMID:The majority of T lymphocytes are polyclonal during the chronic phase of chronic myelogenous leukemia. 859 8


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