Fig. 8. Model of polyadenylation-induced translation. Dormant CPE-containing mRNAs (e.g. cyclin B1) in immature oocytes are bound by CPEB, which in turn is bound to maskin, which in turn is bound to eIF4E, the cap-binding factor. The binding of maskin to eIF4E precludes the binding of eIF4G to eIF4E, thus inhibiting the formation of the initiation complex. The cleavage and polyadenylation specificity factor (CPSF) may or may not be loosely associated with the hexanucleotide AAUAAA at this time. Following progesterone stimulation, the kinase aurora is activated and phosphorylates CPEB Ser174, an event that causes CPEB to bind and recruit CPSF into an active cytoplasmic polyadenylation complex, presumably helping it to associate with the AAUAAA. CPSF recruits poly(A) polymerase (PAP) to the end of the mRNA, where it catalyzes poly(A) addition. The newly elongated poly(A) tail is then bound by poly(A)-binding protein (PABP), which in turn associates with eIF4G. eIF4G, when associated with PABP, then displaces maskin from, and binds to, eIF4E, thereby initiating translation. eIF4G, through eIF3, interacts with the 40S ribosomal subunit.