Changes in nucleotide-binding proteins during oocyte maturation in Xenopus laevis

Photoaffinity nucleotide analogs of ATP and GTP have been used to investigate the purine nucleotide-binding proteins of Xenopus laevis oocytes. These analogs label Xenopus oocyte supernatant proteins in a highly specific manner. The pattern of proteins labeled with these analogs was determined by polyacrylamide gel electrophoresis. A number of changes in this pattern were observed during the time course of progesterone-stimulated maturation in vitro. If one alters the dynamic balance of phosphatase and kinase activities with NaF, these changes are not observed. This photoaffinity approach also provides an assay for the purification of high-affinity nucleotide-binding proteins, including protein kinases, which may be important in the process of oocyte maturation.