Identification of a C-rich element as a novel cytoplasmic polyadenylation element in Xenopus embryos

During Xenopus early development, the length of the poly(A) tail of materna l mRNAs is a key element of translational control. Several sequence element s (cytoplasmic polyadenylation elements) localized in 3' untranslated regio ns have been shown to be responsible for the cytoplasmic polyadenylation of certain maternal mRNAs, Here, we demonstrate that the mRNA encoding the ca talytic subunit of phosphatase 2A is polyadenylated after fertilization of Xenopus eggs. This polyadenylation is mediated by the additive effects of t wo cis elements, one being similar to already described cytoplasmic polyade nylation elements and the other consisting of a polycytosine motif. Finally , a candidate specificity factor for polycytosine-mediated cytoplasmic poly adenylation has been purified and identified as the Xenopus homologue of hu man alpha-CP2. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.