The mRNA 5สน cap regulates splicing, nuclear output, resistance to exonuclease degradation, and initiation of translation. In short, 5' cap has the following functions:
Regulation of nuclear export;
Prevention of degradation by exonucleases;
Promotion of translation;
Promotion of 5' proximal intron excision.
https://mrna.creative-biolabs.com/mrna-5-capping.htm
