Enhanced phosphorylation of yeast endogenous substrates by phosphatidylglycerol (dioleoyl) and phosphatidylinositol.

Protein kinases and their endogenous substrates from the crude cytosolic extract of Saccharomyces cerevisiae were coeluted in the fraction 13 on DE-52 column chromatography. Analyses of SDS-polyacrylamide gel electrophoresis and autoradiography revealed that the peptides between 14 and 34 kDa were the major phosphorylated substrates. In the presence of Ca2+ and Mg2+, the phosphorylation was suppressed strongly by the regulatory subunit of cAMP-dependent protein kinase and slightly by oleic acid, whereas it was augmented appreciably by phosphatidylglycerol (dioleoyl) and phosphatidylinositol.