Cytoplasmic trafficking of IGF-II mRNA-binding protein by conserved KH domains

摘要: The IGF-II mRNA-binding proteins (IMPs), which are composed of two RNA recognition motifs, (RRM) and four hnRNP K homology (KH) domains, have been implicated in subcytoplasmic localization mRNAs during embryogenesis. The IMP family originated via gene duplications before the divergence of vertebrates, IMP homologues consisting only KH motifs have been identified Drosophila Caenorhabditis elegans . Here we characterise trafficking GFP-IMP1 fusion determine the structural determinants for proper cytoplasmic localization. is present large 200-700 nm RNP granules, distributed along microtubules. In motile cells, is transported towards leading edge into cortical region lamellipodia where it connected to microfilaments. Granules travel an ATP-dependent fashion at average speed 0.12 μm/s (range 0.04-0.22 μm/s), cells switch from a delocalized to a localized pattern within 15-20 minutes. Both granule formation unaffected by removal RRMs, whereas deletion mediate RNA-binding, impairs these functions. We conclude that IMP1 associated with motility and that major functions carried out phylogenetically conserved domains.