What are the three major steps in mRNA processing?

The precursor messenger RNA transcript produced from DNA transcription requires many modifications to yield mature messenger RNA that can be subsequently translated into protein. These modifications are called mRNA processing, which includes three major steps.

• 5’ capping: A 7-methylguanosine (m7G) cap is added to the 5’ end of the pre-mRNA.
• 3’ polyadenylation: The 3’ end of pre-mRNA is cleaved, and about 250 adenine residues are added to form a poly(A) tail.
• RNA splicing: Introns are spliced from pre-mRNA and the remaining exons are linked directly to re-form a single continuous molecule, which later can be translated into a protein.