Component of a splicing-dependent multiprotein exon junction complex (EJC) deposited at splice junction on mRNAs. The EJC is a dynamic structure consisting of a few core proteins and several more peripheral nuclear and cytoplasmic associated factors that join the complex only transiently either during EJC assembly or during subsequent mRNA metabolism. Putative component of the spliceosome which enhances the formation of the ATP-dependent A complex of the spliceosome. May participate in mRNA 3'-end cleavage. Also mediates increase of mRNA abundance and translational efficiency 