title: A gene correcting the defect in the CHO mutant Ade -H, deficient in a branch point enzyme (adenylosuccinate synthetase) of de novo purine biosynthesis, is located on the long arm of chromosome 1.
abstract: Somatic hybrids between human cells and the Chinese hamster ovary (CHO) K1 mutant, Ade -H cells, were selected for purine prototrophy by growth in adenine-free medium. The Ade -H mutant is defective in the enzyme adenylosuccinate (AMPS) synthetase (ADSS; EC 6.3.4.4), which carries out the first of a two-step sequence in the biosynthesis of AMP from IMP, and therefore requires exogenous adenine for growth. The presence of the long arm of human chromosome 1 in the hybrids is 100% concordant for the ability to grow in adenine-free medium and restoration of the enzyme activity. Hybrid segregants that lose the ability to grow in adenine-free medium lose all or a portion of chromosome 1 and enzyme activity. Southern blot hybridization with a chromosome 1-specific probe, BCMI, confirms the existence of human chromosome 1 in these hybrids. Analysis of a human/CHO translocation chromosome that arose in one of the hybrids suggests that the gene correcting the defect lies in the region 1 cen-1q12. In summary, we have shown by cytogenetics, segregant analysis, biochemical assay, and Southern blot analysis that human chromosome 1, most likely in the region 1cen-1q12, corrects the defect in ADSS-deficient mutant Ade-H cells.
authors.affiliation: Eleanor Roosevelt Institute for Cancer Research, Denver, Colorado 80206.
authors.forename: L W
authors.initials: LW
authors.lastname: Lai
authors.forename: I M
authors.initials: IM
authors.lastname: Hart
authors.forename: D
authors.initials: D
authors.lastname: Patterson
mesh_terms: D000265:Adenylosuccinate Synthase / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D015139:Blotting, Southern; D002460:Cell Line; D002878:Chromosomes, Human, Pair 1; D006224:Cricetinae; D004247:DNA / Q000032:analysis; D006801:Humans; D006822:Hybrid Cells; D009154:Mutation; D011687:Purines / Q000378:metabolism*
chemical_list: D011687:Purines; D004247:DNA; D000265:Adenylosuccinate Synthase