How does RNA processing affect gene expression?

RNA processing affects gene expression by modifying the mRNA molecule before it leaves the nucleus.

RNA processing is a crucial step in gene expression that occurs in eukaryotic cells. It involves several modifications to the pre-mRNA molecule before it is transported out of the nucleus and translated into a protein. The modifications include capping, splicing, and polyadenylation.

Capping involves the addition of a 7-methylguanosine cap to the 5' end of the mRNA molecule. This cap protects the mRNA from degradation and helps it to bind to ribosomes during translation. Splicing involves the removal of introns, non-coding regions of the pre-mRNA molecule, and the joining of exons, coding regions of the pre-mRNA molecule, to form a mature mRNA molecule. This process allows for alternative splicing, where different combinations of exons can be joined together to produce different protein isoforms from the same gene. Polyadenylation involves the addition of a poly(A) tail to the 3' end of the mRNA molecule. This tail also helps to protect the mRNA from degradation and plays a role in regulating its stability and translation efficiency.

RNA processing can therefore have a significant impact on gene expression by altering the structure and stability of the mRNA molecule. It can also affect the diversity of protein isoforms that can be produced from a single gene. Mutations or dysregulation of RNA processing can lead to a range of diseases, including cancer and genetic disorders.