Structure of protein kinase CK2: dimerization of the human beta-subunit.

Protein kinase CK2 has been shown to be elevated in all so far investigated solid tumors and its catalytic subunit has been shown to serve as an oncogene product. CK2 is a heterotetrameric serine-threonine kinase composed of two catalytic (alpha and/or alpha') and two regulatory beta-subunits. Using the two-hybrid system we could show that the alpha- or alpha'-subunits of CK2 can interact with the beta-subunits of CK2, but not with other alpha- or alpha'-subunits. By comparison, the beta-subunit of CK2 can interact with another beta-subunit. Important amino acids for successful dimerization of the beta-subunit were localized between amino acid residues 156 and 165. Furthermore, we identified residues between amino acid 170 and 180 which antagonize the dimerization.