Fig. 2. IP₃R1 is differentially phosphorylated in Xenopus eggs and zygotes. (A) Western blotting performed on Xenopus egg extracts (approximately three eggs/lane) collected at MII and at interphase (Int) shows MPM2 (upper panel) and IP₃R1 reactivity (lower panel). (B) Immunoprecipitation (IP) experiments performed on MII Xenopus egg extracts using preimmune serum (Preim.), anti-IP₃R1 antibody, MPM2 antibody or beads alone, followed by SDS-PAGE and western blotting with the anti-IP₃R1 antibody (upper panel) and the MPM2 antibody (lower panel).