The pyruvate dehydrogenase complex of Saccharomyces cerevisiae is regulated by phosphorylation

AbstractMitochondria were isolated from Saccharomyces cerevisiae grown on different carbon sources prior to incubation with [γ-32P]ATP. A major 46,000-Mr phosphoprotein, corresponding in Mr value to the El α subunit of the yeast pyruvate dehydrogenase complex (PDC), was detected only in mitochondria isolated from cells grown on a fermentable carbon source such as galactose. Immunoprecipitation with subunit-specific antiserum to the E1 component of mammalian or yeast PDC confirmed the identity of this polypeptide. PDC activity in isolated yeast mitochondria could be inactivated in an ATP-dependent fashion and reactivated in the presence of Ca2+ ions