Article ID Journal Published Year Pages File Type
1946360 Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms 2015 11 Pages PDF
Abstract

•The Scd6/Lsm14b protein xRAPB is expressed during early oogenesis in Xenopus.•xRAPB interacts with the DDX6 helicase Xp54 in poly(A)+mRNP particles.•xRAPB-associated mRNAs are predisposed for translation or intra-cell translocation.

Oocytes accumulate mRNAs in the form of maternal ribonucleoprotein (RNP) particles, the protein components of which determine the location and stability of individual mRNAs prior to translation. Scd6/Lsm14 proteins, typified by RAP55, function in a wide range of eukaryotes in repressing translation and relocating mRNPs to processing bodies and stress granules. In Xenopus laevis, the RAP55 orthologue xRAPA fulfils these functions. Here we describe the properties of a variant of xRAPA, xRAPB, which is a member of the Lsm14B group. xRAPB differs from xRAPA in various respects: it is expressed at high concentration earlier in oogenesis; it interacts specifically with the DDX6 helicase Xp54; it is detected in polysomes and stalled translation initiation complexes; its over-expression leads to selective binding to translatable mRNA species without evidence of translation repression or mRNA degradation. Since both Xp54 and xRAPA are repressors of translation, activation appears to be effected through targeting of xRAPB/Xp54.

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