RNA-binding protein involved in alternative pre-RNA splicing and in cytoplasmic stress granules formation (PubMed:10613902, PubMed:1326761, PubMed:17488725, PubMed:8576255). Shows a preference for uridine-rich RNAs (PubMed:8576255). Activates splicing of alternative exons with weak 5′ splice sites followed by a U-rich stretch on its own pre-mRNA and on TIA1 mRNA (By similarity). Promotes the inclusion of TIA1 exon 5 to give rise to the long isoform (isoform a) of TIA1 (PubMed:17488725). Acts downstream of the stress-induced phosphorylation of EIF2S1/EIF2A to promote the recruitment of untranslated mRNAs to cytoplasmic stress granules (SG) (PubMed:10613902). Possesses nucleolytic activity against cytotoxic lymphocyte target cells (PubMed:1326761). May be involved in apoptosis (PubMed:1326761).
