title: 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.
abstract: 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.
mesh_terms: D000818:Animals; D002459:Cell Fusion; D002874:Chromosome Mapping; D002906:Chromosomes, Human, 6-12 and X; D002999:Clone Cells / Q000201:enzymology / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D008040:Genetic Linkage; D005819:Genetic Markers; D006801:Humans; D006822:Hybrid Cells / Q000201:enzymology / Q000378:metabolism*; D051379:Mice; D010455:Peptides / Q000378:metabolism*; D011955:Receptors, Drug / Q000235:genetics* / Q000378:metabolism; D014178:Translocation, Genetic
chemical_list: D005819:Genetic Markers; D010455:Peptides; D011955:Receptors, Drug; D004815:Epidermal Growth Factor