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

Fertilization results in the biphasic activation of polyphosphoinositide-specific phospholipase C (PLC) activity with an initial increase in activity coincident with the sperm-induced calcium transient, followed by a more sustained increase prior to mitosis. Immunoprecipitation studies demonstrated that the gamma isoform of PLC is present in both the unfertilized and the fertilized egg and contributes to the initial phase of PLC activation. Fertilization also resulted in translocation of a significant fraction of PLC-gamma from the cytosol to the membrane compartment of the egg.