Ras p21 as a potential mediator of insulin action in Xenopus oocytes.
The oncogene protein product (p21) of the ras gene has been implicated in mediating the effects of a variety of growth factors and hormones. Microinjection of monoclonal antibody 6B7, which is directed against a synthetic peptide corresponding to a highly conserved region of p21 (amino acids 29 to 44) required for p21 function, specifically inhibited Xenopus oocyte maturation induced by incubation with insulin. The inhibition was dose-dependent and specific since (i) the same antibody had no effect on progesterone-induced maturation, (ii) immunoprecipitation and Western blotting indicated that the antibody recognized a single protein of molecular weight 21,000 in oocyte extracts, and (iii) inhibition was not observed with identical concentrations of normal immunoglobulin. Thus, p21 appears to be involved in mediating insulin-induced maturation of Xenopus oocytes. Furthermore, the mechanism may involve phosphorylation of p21, as p21 was found to be a substrate of the insulin receptor kinase.
D000818:Animals; D000906:Antibodies; D005260:Female; D007074:Immunoglobulin G; D007328:Insulin / Q000494:pharmacology*; D009857:Oncogenes; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects; D011374:Progesterone / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000502:physiology*; D014982:Xenopus laevis
D000906:Antibodies; D007074:Immunoglobulin G; D007328:Insulin; D011518:Proto-Oncogene Proteins; D011374:Progesterone