The goal of the proposed research is to understand how pp60src functions to regulate structural and biochemical features of the Xenopus oocyte. The nature of cytoskeletal changes caused by expression in oocytes of pp60src with constitutive kinase activity will be examined. The pattern of tyrosine phosphorylation in oocytes producing kinase-constitutive pp60src is altered when such oocytes are made to reenter the cell cycle by progesterone treatment. Activation of the oocyte's endogenous maturation promoting factor (MPF) by microinjection of cyclin mRNA will be used to examine whether MPF is responsible for this change in substrate pattern. Immunochemical and biochemical methods will be used to determine whether changes in pp60src distribution or modification accompany the change in substrate pattern. Site directed mutagenesis will be used in an attempt to define the portion of pp60src which mediates the response to progesterone.
