Immunological characterization of hypoxanthine-guanine phosphoribosyl transferase mutants of mouse L cells: evidence for mutations at different loci in the HGPRT gene

J Cell Physiol. 1975 Apr;85(2 Pt 1):307-20. doi: 10.1002/jcp.1040850217.


A large collection (105) of mouse L cell mutants lacking hypoxanthine-guanine phosphoribosyl transferase activity (HGPRT; E. C. 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.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antigens / analysis*
  • Azaguanine / pharmacology
  • Cell-Free System
  • Cross Reactions
  • Drug Resistance
  • Electrophoresis, Polyacrylamide Gel
  • Epitopes
  • Genes*
  • Hot Temperature
  • Hypoxanthine Phosphoribosyltransferase*
  • Immune Sera
  • L Cells / drug effects
  • L Cells / enzymology
  • L Cells / immunology*
  • Mice
  • Mutation*
  • Precipitin Tests
  • Radioimmunoassay
  • Thioguanine / pharmacology


  • Antigens
  • Epitopes
  • Immune Sera
  • Hypoxanthine Phosphoribosyltransferase
  • Thioguanine
  • Azaguanine