In Vitro Autophosphorylation of Protein Kinase C Isozymes

Abstract

Protein kinase C (PKC) autophosphorylates at multiple sites. Two of these sites that are important for PKC activity are usually quantitatively phosphorylated in vivo (1–8). Therefore, these sites are poorly detected in vitro autophosphorylation studies unless phosphatases are used first to remove endogenous phosphorylation. PKCs also autophosphorylate at other sites that are not quantitatively phosphorylated in cells and are not required for PKC activity (7–14). These sites may nevertheless be important for modulating the activity of PKC (10,12,13). These sites can be isoform specific and may also be important in determining differences in isoform activation.