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Previously, we reported that in clam oocytes, cytoplasmic polyadenylation element-binding protein (CPEB) co-immunoprecipitates with p47, a member of the highly conserved RCK family of RNA helicases which includes Drosophila Me31B and Saccharomyces cerevisiae Dhh1. Xp54, the Xenopus homologue, with helicase activity, is a component of stored mRNP. In(More)
CPEB (cytoplasmic polyadenylation element-binding protein) is an important regulator of translation in oocytes and neurons. Although previous studies of CPEB in late Xenopus oocytes involve the eIF4E-binding protein maskin as the key factor for the repression of maternal mRNA, a second mechanism must exist, since maskin is absent earlier in oogenesis. Using(More)
Clam p82 is a member of the cytoplasmic polyadenylation element-binding protein (CPEB) family of RNA-binding proteins and serves dual functions in regulating gene expression in early development. In the oocyte, p82/CPEB is a translational repressor, whereas in the activated egg, it acts as a polyadenylation factor. Coimmunoprecipitations were performed with(More)
In the transcriptionally inert maturing oocyte and early embryo, control of gene expression is largely mediated by regulated changes in translational activity of maternal mRNAs. Some mRNAs are activated in response to poly(A) tail lengthening; in other cases activation results from de-repression of the inactive or masked mRNA. The 3' UTR cis-acting elements(More)
The Argonaute superfamily is a large family of RNA-binding proteins involved in gene regulation mediated by small noncoding RNA and characterized by the presence of PAZ and PIWI domains. The family consists of two branches, the Ago and the Piwi clade. Piwi proteins bind to 21-30-nucleotide-long Piwi-interacting RNAs (piRNAs), which map primarily to(More)
The RNA helicase p54 (DDX6, Dhh1, Me31B, Cgh-1, RCK) is a prototypic component of P-(rocessing) bodies in cells ranging from yeast to human. Previously, we have shown that it is also a component of the large cytoplasmic polyadenylation element-binding protein translation repressor complex in Xenopus oocytes and that when tethered to the 3' untranslated(More)
RNA-binding proteins play a major part in the control of gene expression during early development. At this stage, the majority of regulation occurs at the levels of translation and RNA localization. These processes are, in general, mediated by RNA-binding proteins interacting with specific sequence motifs in the 3'-untranslated regions of their target RNAs.(More)
Cytoplasmic polyadenylation-element-binding protein (CPEB) is a well-characterized and important regulator of translation of maternal mRNA in early development in organisms ranging from worms, flies and clams to frogs and mice. Previous studies provided evidence that clam and Xenopus CPEB are hyperphosphorylated at germinal vesicle breakdown (GVBD) by cdc2(More)
During early development gene expression is controlled principally at the translational level. Oocytes of the surf clam Spisula solidissima contain large stockpiles of maternal mRNAs that are translationally dormant or masked until meiotic maturation. Activation of the oocyte by fertilization leads to translational activation of the abundant cyclin and(More)
Selective protein synthesis in oocytes, eggs and early embryos of many organisms drives several critical aspects of early development, including meiotic maturation and entry into mitosis, establishment of embryonic axes and cell fate determination. mRNA-binding proteins which (usually) recognize 3'-UTR (untranslated region) elements in target mRNAs(More)