The CWC22 gene encodes an essential splicing factor required for the assembly of the Exon Junction Complex (EJC) on mature mRNAs. CWC22 binds to EIF4A3 and brings it to the EJC, thereby hindering the non-specific binding of EIF4A3 to RNA. The EJC then assembles upstream of mRNA exon junctions and carries out pre-mRNA splicing, mRNA transport, translation, and nonsense-mediated mRNA decay.
The CWC22 protein thus has a key role in the splicing machinery; knockdown of CWC22 has been demonstrated to compromise pre-mRNA splicing in cells. The central region of CWC22, consisting of a conserved MIF4G domain and an MA3 domain, is required for its function.