Required for pre-mRNA splicing as component of thespliceosome. Core component of thesplicing-dependent multiprotein exon junction complex (EJC) depositedat splice junctions on mRNAs. The EJC is a dynamic structure consistingof core proteins and several peripheral nuclear and cytoplasmicassociated factors that join the complex only transiently either duringEJC assembly or during subsequent mRNA metabolism. The EJC marks theposition of the exon-exon junction in the mature mRNA for the geneexpression machinery and the core components remain bound to splicedmRNAs throughout all stages of mRNA metabolism thereby influencingdownstream processes including nuclear mRNA export, subcellular mRNAlocalization, translation efficiency and nonsense-mediated mRNA decay (NMD). The MAGOH-RBM8A heterodimer inhibits the ATPase activity ofEIF4A3, thereby trapping the ATP-bound EJC core onto spliced mRNA in astable conformation. The MAGOH-RBM8A heterodimer interacts with the EJCkey regulator PYM1 leading to EJC disassembly in the cytoplasm andtranslation enhancement of EJC-bearing spliced mRNAs by recruiting themto the ribosomal 48S preinitiation complex. Its removal fromcytoplasmic mRNAs requires translation initiation from EJC-bearingspliced mRNAs. Associates preferentially with mRNAs produced bysplicing. Does not interact with pre-mRNAs, introns, or mRNAs producedfrom intronless cDNAs. Associates with both nuclear mRNAs and newlyexported cytoplasmic mRNAs. The MAGOH-RBM8A heterodimer is a componentof the nonsense mediated decay (NMD) pathway. Involved in the splicingmodulation of BCL2L1/Bcl-X (and probably other apoptotic genes);specifically inhibits formation of proapoptotic isoforms such as Bcl-X (S); the function is different from the established EJC assembly. [1-8]

MADVLDLHEAGGEDFAMDEDGDESIHKLKEKAKKRKGRGFGSEEGSRARMREDYDSVEQDGDEPGPQRSVEGWILFVTGVHEEATEEDIHDKFAEYGEIKNIHLNLDRRTGYLKGYTLVEYETYKEAQAAMEGLNGQDLMGQPISVDWCFVRGPPKGKRRGGRRRSRSPDRRRR