A HIGHLY CONSERVED RNA-BINDING PROTEIN FOR CYTOPLASMIC MESSENGER-RNA LOCALIZATION IN VERTEBRATES

Background: Cytoplasmic mRNA localization is a widespread mechanism fo r restricting the translation of specific mRNAs to distinct regions of eucaryotic cells. This process involves specific interactions between cellular factors and localization signals in the 3' untranslated regi ons of the localized mRNA. Because only a few of these cellular factor s have been identified, it is not known whether common factors are uti lized for the localization of different mRNAs. We recently discovered Vera, a protein that binds specifically to the Vg1 localization elemen t and is involved in the localization of Vg1 mRNA in Xenopus oocytes. Results: To characterize further the role of Vera in the localization of Vg1 mRNA, we have purified the Vera protein and cloned its gene. Ve ra is homologous to chicken zip-code-binding protein (ZBP), which bind s to a short RNA sequence required for localization of beta-actin mRNA in chick embryo fibroblasts. The predicted amino-acid sequences of Ve ra and ZBP contain five RNA-binding domains and putative signals for n uclear localization and export. Like the binding of ZBP to beta-actin mRNA, Vera specifically binds to a repeated sequence motif in the Vg1 localization element that is required for Vg1 mRNA localization in Xen opus oocytes. Conclusions: Vera, a highly conserved component of the m RNA localization machinery, participates in localizing different mRNAs in different cell types. Thus, Vera appears to be a general factor fo r mRNA localization, and additional factors may be required to specify diverse patterns of RNA localization. (C) Current Biology Ltd ISSN 09 60-9822.