Biochemical evidence that the N-terminal segments of the alpha subunit and the beta subunit play interchangeable roles in the activation of protein kinase CK2.

The concept that the amino-terminal segment plays a role in conferring high basal activity to protein kinase CK2 alpha subunit has been validated by generating two mutants (Y26F and delta2-6) which are defective both in catalytic activity and in thermal stability. The additional finding that the activity of the two mutants is fully restored upon association with the regulatory beta subunit, in conjunction with the observation that synthetic peptides reproducing the N-terminal segment (1-30) and the activation loop (175-201) of CK2alpha counteract the functional effects of the C-terminal domain of the beta subunit, is consistent with a mechanism of activation of CK2 where the N-terminal domain of alpha and the C-terminal domain of beta play interchangeable roles.