Specific binding of protein kinase CK2 catalytic subunits to tubulin

Protein kinase CK2 is composed of two regulatory beta-snbnnits and two cata lytic alpha- or alpha'-subunits, To analyse these subunits individually we generated antibodies against unique peptides derived from the alpha-, alpha '- and beta-subunit, Immunofluorescence studies with these antibodies revea led the presence of all three CK2 subunits in the cytoplasm and weakly in t he nucleus with strong signals around the nuclear membrane. Double staining experiments revealed a co-localisation of all three subunits with tubulin, A direct association between the CK2 alpha- and the alpha'-subunit and tub ulin was confirmed by coimmunoprecipitation experiments as well as by Far W estern analysis. There was no binding of the CK2 beta-subunit to tubulin, T hus, with tubulin we have identified a new binding partner specific for the catalytic subunits of CK2, (C) 1999 Federation of European Biochemical Soc ieties.