Phosphorylation activity associated with plasma membrane-cortical granule complex of Xenopus laevis oocytes

Plasma membrane-cortical granule complexes from Xenopus laevis oocytes were isolated by a differential centrifugation procedure. Membrane preparations incorporated 32P from [gamma-32P]ATP predominantly into three protein bands of Mr 128,000, 54,000 and 29,000, as determined by sodium dodecyl-polyacrylamide gel electrophoresis. Progesterone and insulin, added in vitro to membranes, did not produce any change in this phosphorylation pattern, contrary to some previously published results. The availability of enriched membrane complexes should permit further biochemical dissection of signal transduction pathways that are activated during oocyte maturation and fertilization.