Sequence-specific RNA-binding protein that regulates mRNA cytoplasmic polyadenylation and translation initiation during oocyte maturation and early development. Binds to the cytoplasmic polyadenylation element (CPE), an uridine-rich sequence element (consensus sequence 5'-UUUUUAU-3') within the mRNA 3'-UTR. In the absence of phosphorylation and in association with tacc3/maskin, also acts as a repressor of translation of CPE-containing mRNA; a repression that is relieved by phosphorylation or degradation. Requires zinc for RNA binding. Involved in the cell cycle progression from S phase into M phase (By similarity). Found in a complex with cpeb1, tacc3/maskin and eif4e; dissolution of this complex results in the binding of eif4e to eif4g and the translational activation of CPE-containing mRNAs. Found in a complex with cpeb1, cpsf1, the cytoplasmic poly(A) polymerase papd4/gld2 and sympk. Found in a mRNP complex with cpeb1, a guanine exchange factor xgef and mos mRNA. Interacts with cpsf1, papd4/gld2, tacc3/maskin, microtubules, sympk and xgef. Component of a ribonucleoprotein (RNP) complex, at least composed of cpeb1, lsm14b/rap55b, ddx6/Xp54, ybx2/frgy2, pat1/P100, eif4enif1/4E-T and eif4e1b. Interaction with ybx2/frgy2 is RNA-dependent. May interact with aplp1. Interaction with cpsf1 increases during meiotic maturation and is not mediated through RNA. Interaction with xgef is necessary for its early activating phosphorylation status (By similarity). During mitosis localizes with tacc3/maskin and CPE-containing mRNAs to both spindle poles. Membrane-associated. Colocalizes with members of the polyadenylation and translation complex factors (cpsf, aplp1, tacc3/maskin, aurka, etc.), including CPE-containing RNAs (By similarity). The 2 RRM domains and the C-terminal region mediate interaction with CPE-containing RNA. Ser-174 phosphorylation by aurka in immature oocytes is essential to trigger CPE-containing mRNA cytoplasmic polyadenylation and translation activation and the subsequent signaling events that result in meiotic progression. Ser-174 phosphorylation recruits the cleavage and polyadenylation specificity factor (cpsf1) into an active cytoplasmic polyadenylation complex. Ser-174 phosphorylation increases its affinity for cpsf1 and papd4/gld2. Heavily phosphorylated by CDK1 on serines late during oocyte maturation. Ser-210 phosphorylation is sufficient to target cpeb1 for degradation. Ser-174 phosphorylation oscillates with the cell cycle (phosphorylated at M phase, but not at S phase) and is necessary for S phase to M phase progression. Phosphorylation at Ser-174 may be promoted by aplp1 (By similarity). Ubiquitinated. Requires a PEST box and the proteasome pathway for destruction during oocyte maturation. Ser-210 phosphorylation triggers its destruction, an event important to allow the transition from metaphase I to metaphase II and cytokinesis in the early embryo (By similarity). Belongs to the RRM CPEB family.