What is one of the three roles of RNA capping?

RNA capping plays a crucial role in the stability and functionality of mRNA molecules, and one of its primary functions is to protect mRNA from degradation. The 5' cap structure, which is a modified guanine nucleotide added to the beginning of the mRNA transcript, serves as a protective barrier against exonucleases—enzymes that degrade RNA from the ends. This capping also prevents the recognition and degradation of mRNA by cellular surveillance mechanisms that identify incomplete or improperly processed RNA.

In addition to providing protection, the cap structure also facilitates the splicing of introns, assists in the export of mRNA from the nucleus to the cytoplasm, and plays a key role in the initiation of translation by helping ribosomes recognize the mRNA. These functions are essential for the overall stability and translation efficiency of mRNA, allowing the genetic information to be properly expressed.