Ca2+/calmodulin-dependent protein kinase in Saccharomyces cerevisiae

Abstract

Ca2+-dependent chromatography of soluble cytosolic proteins on calmodulin-Sepharose gave a fraction that exhibited Ca2+- and calmodulin-dependent phosphorylation of several polypeptides, including 60, 56 and 45 kDa species. At 0.2 microM beef calmodulin the phosphorylation was optimal at 3 microM free Ca2+, and at 80 microM free Ca2+ it was half-maximal at about 0.1 microM beef calmodulin. It is concluded that the fraction contains calmodulin-dependent protein kinase(s) which is (are) autophosphorylated or associated with substrates.