IUBMB Enzyme Nomenclature


Accepted name: methyltransferase cap2

Reaction: S-adenosyl-L-methionine + a 5'-(N7-methyl 5'-triphosphoguanosine)-(2'-O-methyl-ribonucleotide)-(ribonucleotide)-[mRNA] = S-adenosyl-L-homocysteine + a 5'-(N7-methyl 5'-triphosphoguanosine)-(2'-O-methyl-ribonucleotide)-(2'-O-methyl-ribonucleotide)-[mRNA]

Other name(s): CMTR2 (gene name); MTR2; cap2-MTase; mRNA (nucleoside-2'-O)-methyltransferase (ambiguous)

Systematic name: S-adenosyl-L-methionine:5'-(N7-methyl 5'-triphosphoguanosine)-(2'-O-methyl-ribonucleotide)-ribonucleotide-[mRNA] 2'-O-methyltransferase

Comments: The enzyme, found in higher eukaryotes including insects and vertebrates, and their viruses, methylates the ribose of the ribonucleotide at the second transcribed position of mRNAs and snRNAs. This methylation event is known as cap2. The human enzyme can also methylate mRNA molecules where the upstream ribonucleotide is not methylated (see EC, methyltransferase cap1), but with lower efficiency [2].

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number:


1. Arhin, G.K., Ullu, E. and Tschudi, C. 2'-O-methylation of position 2 of the trypanosome spliced leader cap 4 is mediated by a 48 kDa protein related to vaccinia virus VP39. Mol. Biochem. Parasitol. 147 (2006) 137-139. [PMID: 16516986]

2. Werner, M., Purta, E., Kaminska, K.H., Cymerman, I.A., Campbell, D.A., Mittra, B., Zamudio, J.R., Sturm, N.R., Jaworski, J. and Bujnicki, J.M. 2'-O-ribose methylation of cap2 in human: function and evolution in a horizontally mobile family. Nucleic Acids Res. 39 (2011) 4756-4768. [PMID: 21310715]

[EC created 2014, modified 2021]

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