title: Immunological characterization of hypoxanthine-guanine phosphoribosyl transferase mutants of mouse L cells: evidence for mutations at different loci in the HGPRT gene.
abstract: A large collection (105) of mouse L cell mutants lacking hypoxanthine-guanine phosphoribosyl transferase activity (HGPRT; E. C. 2.4.2.8) were analyzed for the presence of serologically cross reacting material (CRM). Antibody directed against highly purified mouse liver HGPRT was used for detecting DRM activity by two methods: (1) the standard precipitation-inhibition assay; and (2) a radioimmune-precipitation assay. The latter assay proved to have far greater sensitivity for the detection of altered forms of HGPRT. Approximately 40% of the HGPRT- cell lines contain CRM activity (i.e., were CRM+). This indicates that a minimum of 40% of the HGPRT- clones arose as a result of mutations in the HGPRT structural gene. The CRM+ cell lines were shown to contain different levels of CRM activity. Measurements of the heat sensitivity of CRM in the different HGPRT- cell lines showed a broad spectrum of CRM heat inactivation kinetics. These latter two observations provide strong evidence that the mutations giving rise to the HGPRT-CRM+ phenotype occurred at different sites in the HGPRT structural gene.
mesh_terms: D000818:Animals; D000941:Antigens / Q000032:analysis*; D001375:Azaguanine / Q000494:pharmacology; D002474:Cell-Free System; D003429:Cross Reactions; D004351:Drug Resistance; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes; D005796:Genes; D006358:Hot Temperature; D007041:Hypoxanthine Phosphoribosyltransferase; D007106:Immune Sera; D007739:L Cells / Q000187:drug effects / Q000201:enzymology / Q000276:immunology*; D051379:Mice; D009154:Mutation; D011233:Precipitin Tests; D011863:Radioimmunoassay; D013866:Thioguanine / Q000494:pharmacology
chemical_list: D000941:Antigens; D000939:Epitopes; D007106:Immune Sera; D007041:Hypoxanthine Phosphoribosyltransferase; D013866:Thioguanine; D001375:Azaguanine