The model of CPEB dimerization: CPEB dimerizes through the RNA-binding domain. The dimerization prevents excess CPEB from binding to mRNAs, which may cause translational deregulation. Moreover, CPEB dimers have higher affinity for degradation and some polyadenylation factors, which leads to rapid degradation of dimers. Dimer destruction releases the polyadenylation factors for translational activation of CPE-containing mRNA (also see the Discussion). Abbreviations: CPE, cytoplasmic polyadenylation element; HEX, AAUAAA hexanucleotide binding site for CPSF; RBD, RNA-binding domain; CPSF, cleavage and polyadenylation specific factor; ePAB, embryonic poly(A)-binding protein; plx1, polo-like kinase 1; β-TrCP, β-transducin repeat-containing protein–F-box protein of ubiquitin E3 ligase complex; GVBD, germinal vesicle break down.
