EC 2.1.1.56     
Accepted name: mRNA (guanine-N7)-methyltransferase
Reaction: S-adenosyl-L-methionine + a 5′-(5′-triphosphoguanosine)-[mRNA] = S-adenosyl-L-homocysteine + a 5′-(N7-methyl 5′-triphosphoguanosine)-[mRNA]
Glossary: a 5′-(5′-triphosphoguanosine)-[mRNA] = G5′ppp5′R-[mRNA]
a 5′-(N7-methyl 5′-triphosphoguanosine)-[mRNA] = m7G5′ppp5′R-[mRNA] = cap0
Other name(s): RNMT (gene name); ABD1 (gene name); messenger ribonucleate guanine 7-methyltransferase; guanine-7-methyltransferase; messenger RNA guanine 7-methyltransferase; S-adenosyl-L-methionine:mRNA (guanine-7-N)-methyltransferase
Systematic name: S-adenosyl-L-methionine:mRNA (guanine-N7)-methyltransferase
Comments: The terminal N7-methylguanosine facilitates gene expression in eukaryotic cells and is recognized by cap-binding proteins.
References:
1.  Ensinger, M.J., Martin, S.A., Paoletti, E. and Moss, B. Modification of the 5′-terminus of mRNA by soluble guanylyl and methyl transferases from vaccinia virus. Proc. Natl. Acad. Sci. USA 72 (1975) 2525–2529. [PMID: 1058472]
2.  Groner, Y., Gilbao, E. and Aviv, H. Methylation and capping of RNA polymerase II primary transcripts by HeLa nuclear homogenates. Biochemistry 17 (1978) 977–982. [PMID: 629955]
3.  Martin, S.A. and Moss, B. Modification of RNA by mRNA guanylyltransferase and mRNA(guanine-7-)methyltransferase from vaccinia virions. J. Biol. Chem. 250 (1975) 9330–9335. [PMID: 1194287]
4.  Martin, S.A., Paoletti, E. and Moss, B. Purification of mRNA guanylyltransferase and mRNA(guanine-7-)methyltransferase from vaccinia virions. J. Biol. Chem. 250 (1975) 9322–9329. [PMID: 1194286]
5.  Mao, X., Schwer, B. and Shuman, S. Yeast mRNA cap methyltransferase is a 50-kilodalton protein encoded by an essential gene. Mol. Cell Biol. 15 (1995) 4167–4174. [PMID: 7623811]
6.  Pillutla, R.C., Yue, Z., Maldonado, E. and Shatkin, A.J. Recombinant human mRNA cap methyltransferase binds capping enzyme/RNA polymerase IIo complexes. J. Biol. Chem. 273 (1998) 21443–21446. [PMID: 9705270]
7.  Tsukamoto, T., Shibagaki, Y., Niikura, Y. and Mizumoto, K. Cloning and characterization of three human cDNAs encoding mRNA (guanine-7-)-methyltransferase, an mRNA cap methylase. Biochem. Biophys. Res. Commun. 251 (1998) 27–34. [PMID: 9790902]
[EC 2.1.1.56 created 1981]
 
 
EC 2.7.7.50     
Accepted name: mRNA guanylyltransferase
Reaction: GTP + a 5′-diphospho-[mRNA] = diphosphate + a 5′-(5′-triphosphoguanosine)-[mRNA]
Glossary: a 5′-(5′-triphosphoguanosine)-[mRNA] = G(5′)pppPur-mRNA = mRNA containing a guanosine residue linked 5′ through three phosphates to the 5′ position of the terminal residue
Other name(s): RNGTT (gene name); CEG1 (gene name); mRNA capping enzyme; messenger RNA guanylyltransferase; Protein λ2
Systematic name: GTP:mRNA guanylyltransferase
Comments: The human enzyme is a multi domain protein that also has the activity of EC 3.6.1.74, mRNA 5′-phosphatase.
References:
1.  Ensinger, M.J., Martin, S.A., Paoletti, E. and Moss, B. Modification of the 5′-terminus of mRNA by soluble guanylyl and methyl transferases from vaccinia virus. Proc. Natl. Acad. Sci. USA 72 (1975) 2525–2529. [PMID: 1058472]
2.  Groner, Y., Gilbao, E. and Aviv, H. Methylation and capping of RNA polymerase II primary transcripts by HeLa nuclear homogenates. Biochemistry 17 (1978) 977–982. [PMID: 629955]
3.  Itoh, N., Yamada, H., Kaziro, Y. and Mizumoto, K. Messenger RNA guanylyltransferase from Saccharomyces cerevisiae. Large scale purification, subunit functions, and subcellular localization. J. Biol. Chem. 262 (1987) 1989–1995. [PMID: 3029058]
4.  Martin, S.A. and Moss, B. Modification of RNA by mRNA guanylyltransferase and mRNA(guanine-7-)methyltransferase from vaccinia virions. J. Biol. Chem. 250 (1975) 9330–9335. [PMID: 1194287]
5.  Martin, S.A., Paoletti, E. and Moss, B. Purification of mRNA guanylyltransferase and mRNA(guanine-7-)methyltransferase from vaccinia virions. J. Biol. Chem. 250 (1975) 9322–9329. [PMID: 1194286]
[EC 2.7.7.50 created 1981, modified 2021]