Abstract
Using a synthetic peptide corresponding to the sixteen amino-acid N-terminus of the beta subunit, the structure-activity relationship study of casein kinase 2 (CK2) was performed with regard to its previously reported property to polymerize and oligomerize in vitro. Velocity sedimentation experiments show that the peptide beta 1-16 prevents the thick filament formation and stabilizes the ring-like structure of the kinase. Furthermore, the peptide beta 1-16 stimulates the kinase activity by 3-fold toward exogenous substrates as well as the intrinsic autophosphorylation of the kinase. Such observations are in agreement with the proposed model of an activated state of CK2 when the ring-like structure is adopted. Comparison of the effects of spermine and peptide beta 1-16 on CK2 structure and activity suggests that these two activating molecules may function in a different way. Our study suggests that the N-terminal region of the beta subunit of CK2 could regulate the kinase activity by controlling the quaternary structure of the enzyme.
