PKC--a pivotal regulator of early development

Oocytes, eggs and blastomeres of the embryo are special cells that undergo rapid changes in structure and function at developmental transitions. These changes are frequently regulated by cytoplasmic signaling events, particularly at the developmental transition of fertilization, because the genome is largely inactivated at this time. Protein kinase C (PKC) is a signaling agent that acts after the sperm-induced rise in calcium and has a central role in the remodeling of the structure of the egg into the zygote in many species. PKC also acts during other developmental transitions. This kinase serves as a chronometer, which can choreograph the cell's remodeling events in both space and time. Several technical advancements discussed in this review have permitted a better understanding of the actions of PKC.