[Some properties of the reaction catalyzed by protein kinase bound to cardiac sarcolemma].
A highly purified sarcolemmal fraction from rat heart consisted of closed inside-out oriented vesicles and possessed high activities of Na+, K+-ATPase, adenylate cyclase and creatine kinase. Contaminations of sarcolemmal preparation by other membranous fractions were practically absent. This sarcolemmal fraction contained protein kinase tightly bound to the membrane. Substrates of the phosphorylation reaction catalyzed by this protein kinase were either endogenous sarcolemmal protein (proteins) with molecular weight of 11500 or exogenous protein--histone, type II. Phosphorylation of the endogenous but not of the exogenous substrate was completely independent of cyclic AMP. A kinetic analysis of the sarcolemmal protein kinase reaction with Mg[gamma-32P]ATP and histone as substrates revealed that the kinetic mechanism of this reaction is characterized by the following kinetic parameters: Km (Mg-ATP) = 12.1 microM; Km (histone) = 0.47 mg/ml; Ki (Mg-ADP) = 15.6 microM. A comparison of experimental results to literary data allows to suggest that the sarcolemmal enzyme is virtually soluble protein kinase tightly bound to the sarcolemma.
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D003402:Creatine Kinase / Q000378:metabolism; D007700:Kinetics; D008854:Microscopy, Electron; D009206:Myocardium / Q000201:enzymology*; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D012508:Sarcolemma / Q000201:enzymology* / Q000648:ultrastructure; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D011494:Protein Kinases; D003402:Creatine Kinase; D000262:Adenylyl Cyclases; D000254:Sodium-Potassium-Exchanging ATPase
Svoĭstva reaktsii, kataliziruemoĭ proteinkinazoĭ, sviazannoĭ s sarkolemmoĭ serdtsa.