Messenger RNA capping process

The messenger RNA capping process (also known as mRNA capping or five-prime capping) is an enzymatic modification occurring co-transcriptionally in eukaryotes, where a specially modified guanine nucleotide (7-methylguanosine) is added via a 5'-5' triphosphate linkage to the 5′ end of nascent pre-mRNA[1][2][3][4][5][6][7][8][9]. This cap structure stabilizes mRNA by protecting it from exonucleolytic degradation, facilitates nuclear export, marks the RNA as "self," and is essential for efficient translation initiation by recruiting ribosomes and translation initiation factors[1][2][3][4][5][7][8][9]. The capping process involves several sequential enzymatic steps: removal of a terminal phosphate by RNA triphosphatase, addition of GMP by guanylyltransferase, and subsequent methylation by methyltransferase[1][4]. This is a fundamental step in eukaryotic gene expression but is not itself a molecular target or biomolecule; rather, the enzymes responsible for capping may be potential therapeutic targets, not the process itself.

Other names

mRNA capping5′ cappingFive-prime capping