PKC Regulation of Gametogenesis and Early Development

The protein kinase C (PKC) family is comprised of 11 isotypes and many can exist in a single cell simultaneously. There are three general categories of PKC based on their cofactor requirements for activation: The conventional, novel, and atypical PKCs. The first category, the conventional PKC isotypes, are PKC┙, -┚I, -┚II, and -┛ and are activated by diacylglycerol (DAG), and negatively charged phospholipids in a calcium-dependent manner. The second category, the novel PKCs, are composed of PKC├, -┝, -┠, and –┟ and require negatively changed phospholipids and DAG, but act in a calcium-independent manner. Finally, the atypical PKCs are human ┡/mouse ┣ and PKC┞ and only require negatively charged phospholipids for activation. Each PKC isotype phosphorylates serine/threonine residues on protein substrates. There are several known substrates for PKC and they include MARCKS proteins, RACK proteins, Dynamin, EGFR, MEK5, the two subunits of MPF, p34cdc2 and cyclin B, among others (Yu et al., 2004; Steinberg 2008; Meier et al., 2009).