title: Hotspots for spontaneous and mutagen-induced lesions in regulatory subunit of cyclic AMP-dependent protein kinase in S49 mouse lymphoma cells.
abstract: From an S49 mouse lymphoma cell subline that carries an electrophoretic marker mutation in one allele for a regulatory (R) subunit of cyclic AMP-dependent protein kinase, 130 cyclic AMP-resistant mutants were isolated and characterized. Of the 77 independent spontaneous and mutagen-induced isolates identified, 74 had kinases with increased apparent activation constants (KaS) for cyclic AMP-dependent activation. The "Ka" phenotype was invariably correlated with an apparent structural lesion in one R subunit allele. "Charge-shift" lesions in 43 independent isolates were mapped to small regions within the R subunit by two-dimensional gel analysis of partial proteolysis peptides. Nine Ka mutations were distinguished by differences in charge or peptide maps of mutant R subunits, and the mutations were clustered in two regions associated with the cyclic AMP-binding sites of the R subunit. The relative frequencies of different mutations differed among spontaneous, ethyl methanesulfonate-induced, and N-methyl-N'-nitro-N-nitrosoguanidine-induced isolates. Mutation frequencies were also markedly different for the two R subunit alleles; this allele preference was strongest for mutagen-induced lesions in the more carboxy terminal cyclic AMP-binding site.
mesh_terms: D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002352:Carrier Proteins / Q000235:genetics*; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D005020:Ethyl Methanesulfonate / Q000633:toxicity*; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D008223:Lymphoma / Q000201:enzymology*; D008769:Methylnitronitrosoguanidine / Q000633:toxicity*; D051379:Mice; D009153:Mutagens; D009154:Mutation; D010446:Peptide Fragments / Q000032:analysis; D011494:Protein Kinases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009153:Mutagens; D010446:Peptide Fragments; C015482:protein kinase modulator; D008769:Methylnitronitrosoguanidine; D003994:Bucladesine; D005020:Ethyl Methanesulfonate; D011494:Protein Kinases