XGef and CPEB interact throughout oogenesis and until 100% GVBD. (A) XGef and CPEB interact throughout oogenesis and oocyte maturation. Oocyte extracts were prepared from oocytes at different stages of oogenesis (lanes 1–4) and at intervals during progesterone-induced meiotic maturation (lanes 5–13). Protein complexes were immunoprecipitated with anti-XGef antibody from 50 (lanes 1–12) or 250 (*, lane 13) oocytes. Protein G-agarose–bound (IP: XGef) and input (middle) samples were analyzed by SDS-PAGE and immunoblotting with guinea pig anti-CPEB antibody (IB: CPEB). Input samples also were analyzed with anti-XGef antibodies and anti-PCNA antibodies to confirm equivalent sample loading (input, IB: XGef, IB: PCNA, lower two panels). PI, prophase I oocytes; IP, immunoprecipitation; IB, immunoblot; hr in PG, hours in progesterone. (B) Interaction between endogenous CPEB and endogenous XGef does not require RNA. Immunoprecipitations with the indicated antibodies were performed in the presence (+RNAse, lane 3) or absence (lanes 1 and 2) of 10 ng/μl RNAse A. Protein G-agarose–bound (IP) and input samples were analyzed as described above with either anti-CPEB or anti-PCNA antibodies (IB: CPEB or IB: PCNA).