What are exon junction complexes (EJC) responsible for?

Exon junction complexes (EJCs) play a critical role in post-transcriptional regulation of gene expression, specifically in the processing and transport of mRNA molecules. When mRNA is spliced, EJCs are deposited at the junctions between exons. This marks the mRNA as properly spliced and facilitates several downstream processes.

One of the key functions of EJCs is to enhance the stability and export of mRNA from the nucleus to the cytoplasm, ensuring that only correctly spliced transcripts are translated into proteins. Additionally, EJCs are involved in influencing the translation of the mRNA and can also play a role in regulating mRNA degradation under conditions that may involve nonsense-mediated decay, a mechanism that prevents the translation of faulty transcripts.

Therefore, the responsibility of marking properly spliced RNA is central to the function of EJCs, as this marking is instrumental for the mRNA's stability, transport, and translation efficiency.