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)

Transformation frequencies of 4 x 10(-5) were obtained in chromosome-mediated gene transfer experiments using human cell line HeLa S3 as donor and mouse cell line A9 as recipient. This high frequency of interspecific transformation was achieved by treating the recipient cells with dimethylsulfoxide in addition to other facilitators. The high frequency of transformation correlated positively with transgenome size on the basis of both co-transfer of linked markers and chromosome analysis. The syntenic human markers glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NADP(+) 1-oxidoreductase, EC 1.1.1.49) and phosphoglycerate kinase (ATP:3-phospho-D-glycerate 1-phosphotransferase, EC 2.7.2.3) were sometimes transferred together with the selected X-linked prototrophic marker hypoxanthine phosphoribosyltransferase (IMP: pyrophosphate phosphoribosyltransferase, EC 2.4.2.8) into murine somatic cells. Donor human chromosome material could be demonstrated cytologically in some of the transformed cell lines. Transformants exhibited various rates of loss of the human hypoxanthine phosphoribosyltransferase marker when grown under nonselective conditions. These results reveal a broader range of possible interspecific transgenome sizes than has been recognized in the past. The largest transgenomes consist of cytologically detectable donor fragments and contain syntenic markers that are not closely linked to the selected marker.
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PMID:Co-transfer of human X-linked markers into murine somatic cells via isolated metaphase chromosomes. 27 34

Hybrids were obtained from fusions of HPRT-deficient mouse fibroblasts and marsupial lymphocytes. These hybrids retained no identifiable marsupial chromosomes, but all expressed the marsupial form of HPRT. Half the clones also expressed marsupial PGK-A, and half of these also marsupial G6PD; no other marsupial allozyme markers were detected. Since G6PD is known to be sex linked in these species, we conclude that Hpt and Pgk-A are also located on the X chromosome and the markers lie in the order Hpt-Pgk-A-Gpd.
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PMID:Marsupial--mouse cell hybrids containing fragments of the marsupial X chromosome. 29 Nov 29

We produced somatic cell hybrids between HT 1080-6TG human fibrosarcoma cells and either rat white blood cells (WBC) or cells directly derived from rat spleen. Karyologic and isozyme analyses of hybrid cells indicated that they preferentially lose rat chromosomes. Hypoxanthine-aminopterine thymidine-selected hybrid clones expressing rat hypoxanthine phosphoribosyltransferase (HPRT), glucose-6-phosphate dehydrogenase (G6PD), and phosphoglycerate kinase (PGK) and containing the rat X chromosome were counterselected in a medium containing 30 micrograms/ml of 6-thioguanine. Concordant loss of the rat X chromosome and of the expression of rat HPRT and G6PD was observed in the hybrid clones.
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PMID:Segregation of rat chromosomes in somatic cell hybrids between rat cells and HT 1080 human fibrosarcoma cells. 29 42

The behaviour of human cells arrested in mitosis can be severely perturbed so as to generate numerous small minisegregants containing very few chromosomes. These cells can be separated according to size and DNA content and fused with intact cells. In this paper we describe the production and some properties of proliferating cell hybrids generated by fusion of human minisegregant cells derived from a HeLa strain with mouse A9 cells deficient in hypoxanthine phosphoribosyltransferase (HPRT, EC 2.4.2.8). The hybrids were shown to contain up to 10 human chromosomes including a single X. Independently derived hybrid clones were quantitatively characterized and compared with the parental phenotypes with respect to HPRT. Human isozymes of each of the 3 enzymes HPRT, glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and phosphoglycerate kinase (EC 2,7.2.3) were found. Tests to evaluate both structure and function of HPRT were utilized. The specific activity of HPRT of more than 10 hybrids tested was approximately 10% that of the HeLa parent. Structural characterization of HPRT from hybrid cells as evidenced by heat inactivation and electrophoretic mobility results in a 'human-like' phenotype. Functional characterization of parental HPRT results in kinetic constants for cofactor and substrate which do not permit distinction of human and of human and mouse enzymes; HPRT from the minisegregant hybrids had normal kinetic constants. The reduced specific activity of HPRT in the hybrids is discussed in terms of the inability of the mouse environment to regulate the full expression of the human structural gene.
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PMID:Transfer of human chromosomes via human minisegregant cells into mouse cells and the quantitation of the expression of hypoxanthine phosphoribosyltransferase in the hybrids. 56 87

Four diploid somatic recombinants were isolated from hybrids either between or within two diploid cell lines of a male Indian muntjac after HVJ virus-mediated cell fusion. Both parental lines had a normal male karyotype, 7,X,Y1,Y2, in which the largest autosomal pair was heteromorphic with respect to the size of the secondary constriction (1h+/1h-), C bands, and nucleolar organizers. Of the four recombinants, three showed a 6,XX,1h+/1h+ or 1h+/1h- karyotype, the remaining one a 7,XY1Y2,1h+/1h+. No late-replicating X chromosome was found in the XX recombinants, although it was demonstrated in the natural XX line, suggesting the presence of two active X chromosomes in the former. The G6PD, PGK, and HPRT activities were proportional to the number of active X chromosomes present in all cell types examined, indicating their X-linkage, whereas the same level of activities obtained for LDH and 6PGD indicated their autosomal linkage.
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PMID:Euploid somatic recombinants with two active X or XY (1)Y(I) chromosomes isolated from cultured male Indian Muntjac cells after HVJ virus fusion, and their use for gene assignment. 56 83

Analysis of six enzymes using starch gel electrophoresis indicates that autosomal and X-linked genes of both parental species are expressed normally in M. musculus X M. caroli hybrids. There is no evidence for allelic repression for the four autosomally inherited enzymes. Banding patterns for G6PD and PGK-1 indicate that X-chromosome inactivation occurs and that the maternally derived M. musculus X-chromosome is preferentially expressed in the yolk sac. Despite normal genetic expression none of the four adult female hybrids was fertile and the male hybrids tended to be retarded during fetal development. The routine production of fetal M. musculus X M. caroli hybrids, heterozygous for three X-linked genes coding for G6PD, PGK-1, and HPRT, should provide an excellent system for the analysis of X-chromosome expression and an alternative to the mule for studies of hybrid reproduction and development.
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PMID:Mus musculus x Mus caroli hybrids: mouse mules. 74 73

The structural gene for purine-nucleoside phosphorylase (NP) has been assigned to a subregion of chromosome 14 by somatic cell hybridization of male and female cells containing the balanced translocation t(X;14) (p22;q21). Peripheral lymphocytes were fused to a pseudodiploid HPRT-deficient established Chinese hamster cell line. 23 primary hybrid clones (10 derived from male and 13 from female cells) were isolated and maintained in HAT selective medium. Parallel subcultures from generations 16, 24, and 40 after clonal isolation were fully karyotyped and analyzed electrophorectically for expression of the human types of NP, HPRT, G6PD, and PGK. The human NP phenotype segregated discordantly with each human chromosome except chromosome 14 and the der(14),t(X;14) translocation chromosome. In all, 8 hybrids which had retained the der(X), t(X;14) translocation chromosome under HAT selective pressure and expressed human HPRT had lost the human NP phenotype. These results indicate localization of the NP gene in region 14pter leads to 14q21.
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PMID:Intrachromosomal gene mapping in man: assignment of nucleoside phosphorylase to region 14cen leads to 14q21 by interspecific hybridization of cells with a t(X;14) (p22;q21) translocation. 82 89

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

Human genes coding for hypoxanthine phosphoribosyltransferase (HPRT, EC 2.4.2.8; IMP:pyrophosphate phosphoribosyltransferase), glucose-6-phosphate dehydrogenase (G6PD, EC 1.1.1.49; D-glucose-6-phosphate:NADP+ 1-oxidoreductase), and phosphoglycerate kinase (PGK, EC 2.7.2.3; ATP:3-phospho-D-glycerate 1-phosphotransferase) have been assigned to specific regions on the long arm of the X chromosome by somatic cell gentic techniques. Gene assignment and linear order were determined by employing human somatic cells possessing an X/9 translocation or an X/22 translocation in man-mouse cell hybridization studies. The X/9 translocation involved the majority of the X long arm translocated to chromosome 9 and the X/22 translocation involved the distal half of the X long arm translocated to 22. In each case these rearrangements appeared to be reciprocal. Concordant segregation of X-linked enzymes and segments of the X chromosome generated by the translocations indicated assignment of the PGK gene to a proximal long arm region (q12-q22) and the HPRT and G6PD genes to the distal half (q22-qter) of the X long arm. Further evidence suggests a gene order on the X long arm of centromere-PGK-HPRT-G6PD.
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PMID:Human X-Linked genes regionally mapped utilizing X-autosome translocations and somatic cell hybrids. 105 18

We have transferred the human gene for hypoxanthine-guanine phosphoribosyltransferase (HPRT, EC 2.4.2.8; IMP:pyrophosphate phosphoribosyltransferease) via isolated metaphase chromosomes from human HeLa S3 cells into murine A9 cells which lack functional murine HPRT activity, using the technique of McBride and Ozer (Proc, Nat. Acad. Sci. USA 70, 1258-1262, 1973). Three transformed clones were isolated which contained human HPRT activity as determined by electrophoretic and immunochemical assays. Twenty human isozymes other than HPRT whose genes have been assigned to 14 human chromosomes were found to be absent in our transformed clones. Moreover, the human isozymes of hlucose-6-phosphate dehydrogenase (EC 1.1.1.49; D-glucose 6-phosphate:NADP 1-oxidoreductase) and phosphoglycerate kinase (EC 2.7.2.3;ATP:3-phospho-D-glycerate 1-phosphotransferase), whose genes have been linked with the HPRT gene to the long are of the human X chromosome, were also absent. On the basis of the known linkage relationships of the three markers, we thereby suggest that the transferred piece of human genetic material is smaller than 20% of the human X chromosome or less than 1% of the human genome. This estimate assumes a normal syntenic relationship for the long arm of the X chromosome in HeLa S3 cells. In agreement with this conclusion, no human chromosomes could be detected in our transformed clones. When grown under nonselective conditions about 3% of the gene transfer cells lost the human HPRT marker per cell generation. Transformants that had lost human HPRT activity were subjected to hypoxanthine-aminopterin-thymidine selection. The frequency of revertants to the HPRT(+) phenotype was less than 1 x 10(-6), and two revertants that were obtained possessed the mouse electrophoretic phenotype. These results argue against a stable integration of the human donor genetic material into the mouse recipient genome.
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PMID:Transfer of the human gene for hypoxanthine-guanine phosphoribosyltransferase via isolated human metaphase chromosomes into mouse L-cells. 105 70


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