Immunological Detection and Characterization of Poly(A) Polymerase, Poly(A)-Binding Protein and Cytoplasmic Polyadenylation Element-Binding Protein in Goldfish and Xenopus Oocytes

Abstract Cytoplasmic polyadenylation regulates translational activation of dormant cyclin B1 mRNA stored in immature oocytes, a process required for the initiation of oocyte maturation in goldfish and Xenopus. As a first step towards understanding the molecular mechanisms of translational activation of cyclin B1 during oocyte maturation, we have isolated cDNA clones encoding proteins involved in cytoplasmic polyadenylation and produced specific antibodies against recombinant proteins. These include poly(A) polymerase (PAP), poly(A)-binding protein (PABP) and cytoplasmic polyadenylation element-binding protein (CPEB). Monoclonal antibodies raised against goldfish PAP recognized several forms of PAP in goldfish and Xenopus oocytes. Besides ordinary PAPs with high molecular weight (ca. 100 kDa), the antibodies also detected those with low molecular weight (ca. 40 kDa) that are present specifically in the cytoplasm, raising new players that might be responsible for cytoplasmic polyadenylation. An antibody aga...