Reactome | mRNA Capping

mRNA Capping

Stable Identifier

R-HSA-72086

DOI

10.3180/REACT_1470.1

Type

Pathway

Species

Homo sapiens

Compartment

nucleoplasm

ReviewStatus

5/5

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The 5'-ends of all eukaryotic pre-mRNAs studied thus far are converted to cap structures. The cap is thought to influence splicing of the first intron, and is bound by 'cap-binding' proteins, CBP80 and CBP20, in the nucleus. The cap is important for translation initiation, and it also interacts with the poly(A)terminus, via proteins, resulting in circularization of the mRNA to facilitate multiple rounds of translation. The cap is also important for mRNA stability, protecting it from 5' to 3' nucleases, and is required for mRNA export to the cytoplasm.
The capping reaction usually occurs very rapidly on nascent transcripts; after the synthesis of only a few nucleotides by RNA polymerase II. The capping reaction involves the conversion of the 5'-end of the nascent transcript from a triphosphate to a diphosphate by a RNA 5'-triphosphatase, followed by the addition of a guanosine monophosphate by the mRNA guanylyltransferase, to form a 5'-5'-triphosphate linkage. This cap is then methylated by 2'-O-methyltransferases.

Literature References

PubMed ID	Title	Journal	Year
10395561	Coupling RNA polymerase II transcription with pre-mRNA processing. Bentley, D	Curr Opin Cell Biol	1999
11017188	The ends of the affair: capping and polyadenylation. Manley, JL, Shatkin, AJ	Nat Struct Biol	2000
3326038	Messenger RNA capping enzymes from eukaryotic cells. Mizumoto, K, Kaziro, Y	Prog Nucleic Acid Res Mol Biol	1988
11909521	Integrating mRNA processing with transcription. Furger, A, Dye, MJ, Proudfoot, NJ	Cell	2002