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 (2A0) with Km values of 5,0.3 and 1 μM, respectively. Dissociation of protein kinase by cAMP preferentially increased the dephosphorylation of RII by phosphatase-1c, whereas polycations (histone H1 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 μM.
- cyclic AMP dependence Protein kinase Phosphorylase a Protein phosphatase Polybrene
ASJC Scopus subject areas
- Structural Biology
- Molecular Biology
- Cell Biology