A. Dembinsky et al., AUTOPHOSPHORYLATION OF DICTYOSTELIUM MYOSIN-II HEAVY CHAIN-SPECIFIC PROTEIN-KINASE-C IS REQUIRED FOR ITS ACTIVATION AND MEMBRANE DISSOCIATION, The Journal of biological chemistry, 272(2), 1997, pp. 828-834
Myosin II heavy chain (MHC) specific protein kinase C (MHC-PKC) isolat
ed from the ameba, Dictyostelium discoideum, regulates myosin II assem
bly and localization in response to the chemoattractant cAMP. cAMP sti
mulation of Dictyostelium cells leads to translocation of MHC-PKC from
the cytosol to the membrane fraction, as well as causing an increase
in both MHC-PKC phosphorylation and its kinase activity. MHC-PKC under
goes autophosphorylation with each mole of kinase incorporating about
20 mol of phosphate. The MHC-PKC autophosphorylation sites are thought
to be located within a domain at the COOH-terminal region of MHC-PKC
that contains a cluster of 21 serine and threonine residues. Here we r
eport that deletion of this domain abolished the ability of the enzyme
to undergo autophosphorylation in vitro. Furthermore, after this dele
tion, cAMP dependent autophosphorylation of MHC-PKC as well as cAMP-de
pendent increases in kinase activity and subcellular localization were
also abolished. These results provide evidence for the role of autoph
osphorylation in the regulation of MHC-PKC and indicate that this MHC-
PKC autophosphorylation is required for the kinase activation in respo
nse to cAMP and for subcellular localization.