title: Substrate specificity of the cyclic AMP-dependent protein kinase.
abstract: The protein substrate specificity of the catalytic subunit of rabbit skeletal muscle cyclic AMP-dependent protein kinase (EC 2.7.1.37; ATP:protein phosphotransferase) has been studied using genetic variants of beta casein. It was found that beta casein-B was phosphorylated at a much greater rate than beta caseins A1, A2, A3, or C. The enhanced phosphorylation of beta casein-B, as compared with the most common variant A2, was attributed to an arginine substitution for a serine at position 122, which caused a nearby residue, serine 124, to become a phosphorylation site for the protein kinase. These results further support the concept that the local primary structure is important in specificity and that arginine may be a specific determinant common to all the local phosphorylation site sequences recognized by the cyclic AMP-dependent protein kinase.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002364:Caseins / Q000378:metabolism; D009132:Muscles / Q000201:enzymology; D011494:Protein Kinases / Q000378:metabolism*; D011817:Rabbits; D013329:Structure-Activity Relationship
chemical_list: D002364:Caseins; D011494:Protein Kinases