Figure 1.

CPEB activity during prophase I. (A) E16.5 oocyte chromatin from wild-type and CPEB knockout animals was immunostained for SCP1 and SCP3. The filaments in the wild-type oocytes are synaptonemal complexes, which are absent in the knockout oocytes. (B) Extracts prepared from wild-type E16.5 and E18.5 ovaries were supplemented with recombinant CPEB containing a wild-type or mutated aurora phosphorylation site, together with γ³²P-ATP. After incubation, CPEB was gel isolated, digested with trypsin, and analyzed by two-dimensional phospho-peptide mapping. The horizontal arrow denotes a reference peptide that is present in all panels. The white vertical arrow denotes the phospho-peptide containing the aurora phosphorylation site, which, although present when the E16.5 ovary extract was used as the kinase source (cf. wild-type and mutant CPEB proteins), was absent when the E18.5 ovary extract was the kinase source.