Hotspots for spontaneous and mutagen-induced lesions in regulatory subunit of cyclic AMP-dependent protein kinase in S49 mouse lymphoma cells.

摘要: From an S49 mouse lymphoma cell subline that carries electrophoretic marker mutation in one allele for a regulatory (R) subunit of cyclic AMP-dependent protein kinase, 130 AMP-resistant mutants were isolated and characterized. Of the 77 independent spontaneous mutagen-induced isolates identified, 74 had kinases with increased apparent activation constants (Kas) activation. The “Ka” phenotype was invariably correlated structural lesion R allele. “Charge-shift” lesions 43 mapped to small regions within by two-dimensional gel analysis partial proteolysis peptides. Nine Ka mutations distinguished differences charge or peptide maps mutant subunits, clustered two associated AMP-binding sites subunit. relative frequencies different differed among spontaneous, ethyl methanesulfonate-induced, N-methyl-N′-nitro-N-nitrosoguanidine-induced isolates. Mutation also markedly alleles; this preference strongest more carboxy terminal site.