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.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 56941-23-2
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]