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 hetero-tetrameric serine-threonine kinase composed of two catalytic (α and/or α′) and two regulatory β-subunits. Using the two-hybrid system we could show that the α- or α′-subunits of CK2 can interact with the β-subunits of CK2, but not with other α- or α′-subunits. By comparison, the β-subunit of CK2 can interact with another β-subunit. Important amino acids for successful dimerization of the β-subunit were localized between amino acid residues 156 and 165. Furthermore, we identified residues between amino acid 170 and 180 which antagonize the dimerization.
