TYROSINE KINASE SIGNALING AT FERTILIZATION

The unfertilized egg is a highly differentiated cell that retains unli mited developmental potential. The execution of that potential require s signal transduction pathways that release the egg from its quiescent metabolic state, direct the union of the maternal and paternal genome , and initiate a developmental program that will guide embryogenesis. The egg is equipped with an array of cytosolic as well as cell surface receptor protein tyrosine kinases as part of a preassembled signal tr ansduction mechanism. These protein tyrosine kinases have been found t o act at several points during this egg activation process, beginning as early as the initial sperm-egg interaction. While many of these kin ase functions are common to all cells, several functions unique to fer tilization demonstrate the versatility of this class of protein kinase s. (C) 1997 Academic Press.