Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.2.8 (hypoxanthine-guanine phosphoribosyltransferase)
 2,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 680-kb yeast artificial chromosome (YAC) that contains a functional copy of the human hypoxanthine phosphoribosyltransferase (HPRT) gene has been isolated. This YAC, yHPRT, and another YAC, yXY837, which contains the 3' end of the HPRT gene, have been mapped with restriction enzymes that cleave human DNA infrequently. The HPRT gene lies near the center of yHPRT. Fusion of yHPRT-containing yeast spheroplasts with mouse L A-9 cells, which are HPRT-negative, gives rise to HPRT-positive colonies. These colonies contain the human HPRT gene and express human HPRT mRNA. Fusion of yeast with mammalian cells is an efficient way of testing the integrity and functionality of human DNA contained in YACs.
 ...
PMID:The human HPRT gene on a yeast artificial chromosome is functional when transferred to mouse cells by cell fusion. 203 99

Methylation sensitive restriction enzymes were used to evaluate the methylation level of several restriction sites near human hypoxanthine phosphoribosyltransferase (HPRT) genes on active and inactive X chromosomes. DNA samples from leukocytes, from clonally derived fibroblasts, and from independent mouse-human hybrid lines isolated from the fusion of A-9 cells and these clonally derived human cells were studied. Comparison of the methylation patterns shows that restriction sites may show variable or constant methylation among tissues and clones, and heritability of methylation is also different among restriction sites. Methylation is more stable at sites whose methylation status correlate well with HPRT activity. Our results suggest that the methylation of certain cytosine residues may critically affect gene activity and that the methylation pattern of these sites is stably inherited.
 ...
PMID:Stability of DNA methylation of the human hypoxanthine phosphoribosyltransferase gene. 300 50

Linear and circular forms of a 660-kb yeast artificial chromosome (YAC) containing the human hypoxanthine phosphoribosyltransferase gene were introduced into mouse L A-9 cells by fusion with yeast spheroplasts, and in situ hybridization was used to determine the location and fate of the yeast- and YAC-derived DNA in 25 fusion cell lines. Human and yeast DNAs were observed as extrachromosomal DNA molecules, present at least 27 cell divisions after fusion, in half the cell lines. The extrachromosomal molecules replicate extrachromosomally but segregate poorly like plasmids that contain an autonomously replicating sequence element in yeast. This system may allow analysis of DNA requirements for replication and segregation in mammalian cells. The extrachromosomal elements resemble double minutes (DMs), and in five cell lines human and yeast DNAs were present as very large integrated blocks of DNA resembling homogeneously staining regions (HSRs). Thus, the fusion cell lines contain the two characteristic forms of amplified DNA observed in cancer cell lines, DMs and HSRs, indicating that these can be formed from fragments of DNA introduced by cell fusion.
 ...
PMID:Extrachromosomal maintenance and amplification of yeast artificial chromosome DNA in mouse cells. 840 77