Figure 1. Model of Poly(A) tail dynamics of CPE-containing mRNA. CPEB is always bound to the CPE consensus sequence, indicating CPEB and CPE in both translational repression and translational activation. Prior to exit from the nucleus, mRNAs have long poly(A)⁺ tails that are shortened upon entrance into the cytoplasm by the interaction of CPEB, the poly(A)-specific RNase (PARN), and the poly(A) polymerase, Gld2, thereby promoting translational repression. CPEB, PARN, and Gld2 are held together in the ribonucleoprotein (RNP) complex maintained by the scaffold protein symplekin, which also interacts with the cleavage and polyadenylation specificity factor (CPSF). During translational activation CPEB is phosphorylated by Aurora A, resulting in the release of PARN from CPEB and Gld2 and subsequent initiation of poly(A)⁺ tail elongation by Gld2. Reprinted from reference [27], Molecular Cell, 24, Kim Jong Heon, Richter Joel D, Opposing polymerase-deadenylase activities regulate cytoplasmic polyadenylation, pages 173-183, copyright 2006, with permission from Elsevier Limited, Oxford, UK.