Required for pre-mRNA splicing as component of the spliceosome. As a component of the minor spliceosome, involved in the splicing of U12-type introns in pre-mRNAs (By similarity). Promotes exon-junction complex (EJC) assembly. Hinders EIF4A3 from non-specifically binding RNA and escorts it to the splicing machinery to promote EJC assembly on mature mRNAs. Through its role in EJC assembly, required for nonsense-mediated mRNA decay.
Subcellular locations: Nucleus, Nucleus speckle
Concentrates around speckles, which are sites of pre-mRNA synthesis and processing, where it colocalizes with EJC core proteins.