Partner of Y14 and mago (Pym1)

Key regulator of the exon junction complex (EJC), a multiprotein complex that associates immediately upstream of the exon-exon junction on mRNAs and serves as a positional landmark for the intron exon structure of genes and directs post- transcriptional processes in the cytoplasm like mRNA export, nonsense-mediated mRNA decay (NMD) or translation. Acts as an EJC disassembly factor, allowing translation-dependent EJC recycling and removal by interrupting older EJC from spliced mRNAs.

Its association with the 40S ribosomal subunit probably prevents a translation-independent disassembly of the EJC from spliced mRNAs, by restricting its activity to mRNAs which have been translated. Interferes with NMD and enhances translation of spliced mRNAs, probably by antagonizing EJC functions (By similarity).