Regulatory subunit of type II cAMP-dependent protein kinase as substrate and inhibitor of protein phosphatase-1 and -2A.
The dissociated regulatory subunit (RII) of autophosphorylated cAMP-dependent protein kinase II was dephosphorylated by the catalytic subunits of protein phosphatase-1 and -2A (phosphatase-1c and -2Ac) and by a high-Mr polycation-dependent form of phosphatase-2A (2Ao) with Km values of 5, 0.3 and 1 microM, respectively. Dissociation of protein kinase by cAMP preferentially increased the dephosphorylation of RII by phosphatase-1c, whereas polycations (histone Hl or polybrene) markedly stimulated phosphatase-2Ac and -2Ao even in the absence of cAMP. Thiophosphorylated RII inhibited the dephosphorylation of phosphorylase a by these phosphatases with half-maximum inhibitory concentrations of 0.1-0.36 microM.
D000818:Animals; D002412:Cations; D002417:Cattle; D000242:Cyclic AMP / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D006583:Hexadimethrine Bromide / Q000494:pharmacology; D007700:Kinetics; D008345:Manganese / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010762:Phosphorylase a / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism* / Q000494:pharmacology; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2
D002412:Cations; D008345:Manganese; D006583:Hexadimethrine Bromide; D000242:Cyclic AMP; D010762:Phosphorylase a; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2