title: A structural gene mutation affecting the regulatory subunit of cyclic AMP-dependent protein kinase in mouse lymphoma cells.
abstract: Compared to the wild-type parental line of S49 mouse lymphoma cells, intact cells of a mutant line (kin.A) are 10-fold less sensititive to biologic effects of exogenous cyclic adenosine 3':5'-monophophosphate (cAMP), such as induction of cAMP phosphodiesterase, cell cycle-specific growth inhibition, and cytolysis. The cAMP-dependent protein kinase (ATP:protein phosphotransferase; EC 2.7.1.37) activity of kin.A cells exhibits an apparent Ka for activation by cAMP 10-fold greater than that of wild type, and is much more resistant to inactivation by heat. These differences between the wild-type and mutant enzymes persist through a high degree of purification, suggesting a structural alteration in the kin.A holoenzyme. Heterologous reconstitution experiments, using separated R and C subunits of the wild-type and kin.A cAMP-dependent kinases, show that the altered cAMP affinity and thermolability are conferred by the R component of the kin.A enzyme. These results are most consistent with a structural mutation in the kin.A gene coding for the R subunit of cAMP-dependent protein kinase. Evidence for a structural mutation helps to define one mechanism of heritable variation in cultured somatic cells. The phenotype produced by the kin.A structural mutation also greatly strengthens the conslusion that cAMP-dependent protein  kinase is essential for cAMP regulation of growth and enzyme induction in intact S49 cells.
mesh_terms: D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism / Q000494:pharmacology; D004355:Drug Stability; D004789:Enzyme Activation / Q000187:drug effects; D005796:Genes; D006579:Heterozygote; D006720:Homozygote; D006358:Hot Temperature; D007700:Kinetics; D009154:Mutation; D014176:Protein Biosynthesis; D011489:Protein Denaturation; D011494:Protein Kinases / Q000096:biosynthesis* / Q000302:isolation & purification / Q000378:metabolism; D011955:Receptors, Drug; D014158:Transcription, Genetic
chemical_list: D011955:Receptors, Drug; D000242:Cyclic AMP; D011494:Protein Kinases