1,2‐diacylglycerols mimic phorbol 12‐myristate 13‐acetate activation of the sea urchin egg

Phorbol diesters have been reported to stimulate the Na + /H + antiport of a variety of cells including sea urchin eggs. Since stimulation of the Na + /H + antiport is necessary for metabolic derepression during fertilization and protein kinase C is a target of phorbol diesters, enhanced Na + /H + exchange during fertilization may be a result of protein kinase C activity. Protein kinase C is probably physiologically activated by diacylglycerols, which are derived from hydrolysis of phosphatidylinositol. Treatment of sea urchin eggs with 1,2‐diacylglycerols was found to stimulate the Na + /H + antiport. The 1,3‐isomers were without effect. Further, the effects of 1,2‐diacylglycerol and phorbol diester are not additive with respect to Na + /H + exchange. While a direct participation of protein kinase C activity during fertilization remains to be demonstrated, these data support the hypothesis that protein kinase C activity plays a role in fertilization. However, the cytotoxic effect of protein kinase C activators suggests effects associated with their pleiotropic nature.