High phosphorylation of HBV core protein by two alpha-type CK2-activated cAMP-dependent protein kinases in vitro.

Two alpha-type CK2-activated PKAs (CK2-aPKAIalpha and CK2-aPKAIIalpha) were biochemically characterized in vitro using GST-HBV core fusion protein (GST-Hcore) and GST-Hcore157B as phosphate acceptors. It was found that (i), in the absence of cAMP, these two CK2-aPKAs phosphorylated both Ser-170 and Ser-178 on GST-Hcore and Hcore157B; (ii) this phosphorylation was approx. 4-fold higher than their phosphorylation by cAMP-activated PKAs; and (iii) suramin effectively inhibited the phosphorylation of Hcore157B by CK2-aPKAIIalpha through its direct binding to Hcore157B in vitro.

A novel CK2-mediated activation of type II cAMP-dependent protein kinase through specific phosphorylation of its regulatory subunit (RIIalpha) in vitro.

The physiological significance of the casein kinase 2 (CK2)-mediated phosphorylation of type II cAMP-dependent protein kinase (PKAIIalpha) and free type II regulatory (R) subunit (RIIalpha) on their activities was mainly investigated in vitro. In these experiments, [gamma-32P]GTP was used as a phosphate donor for the CK2-mediated phosphorylation of free RIIalpha and PKAIIalpha (bovine heart) in vitro. It was found that: (i).