Identification and characterization of the gene encoding human cytoplasmic polyadenylation element binding protein

The maturation of human oocytes occurs in the absence of gene transcription. In model organisms, such as Drosophila, Xenopus, and the mouse, oocyte maturation and early pattern formation is mediated through the regulated translation of maternally derived mRNAs. The maturation-dependent stimulation of maternal mRNA translation is correlated with increases in poly(A) tail length, controlled through a process termed cytoplasmic polyadenylation. However, this mechanism of mRNA translational control has not been characterized in humans. In this study we report the cloning of a human cytoplasmic polyadenylation element binding (hCPEB) protein with sequence-specific RNA binding activity. Our data demonstrate that alternative splicing generates hCPEB mRNAs that encode proteins with a conserved C-terminal RNA binding domain but with different N-terminal regulatory domains. The hCPEB mRNA is expressed in the brain and heart as well as in immature oocytes, consistent with the hypothesis that cytoplasmic polyadenylation may regulate the translation of human mRNAs in both oocytes and somatic cells.