Fertilization-induced activation of phospholipase C in the sea urchin egg

Fertilization results in the biphasic activation of polyphosphoinositide-sp ecific phospholipase C (PLC) activity with an initial increase in activity coincident with the sperm-induced calcium transient, followed by a more sus tained increase prior to mitosis. Immunoprecipitation studies demonstrated that the gamma isoform of PLC is present in both the unfertilized and the f ertilized egg and contributes to the initial phase of PLC activation. ferti lization also resulted in translocation of a significant fraction of PLC-ga mma from the cytosol to the membrane compartment of the egg. (C) 1999 Acade mic Press.