methyltransferase cap1 activity https://github.com/geneontology/go-ontology/issues/27387 messenger ribonucleate nucleoside 2'-methyltransferase activity Reactome:R-HSA-9694521 Reactome:R-HSA-9694721 RHEA:67020 Reactome:R-HSA-9684033 Reactome:R-HSA-9684032 Reactome:R-HSA-9684030 Reactome:R-HSA-9834003 messenger RNA (nucleoside-2'-)-methyltransferase activity Catalysis of the reaction: a 5'-end (N(7)-methyl 5'-triphosphoguanosine)-ribonucleoside in mRNA or snRNA + S-adenosyl-L-methionine = a 5'-end (N(7)-methyl 5'-triphosphoguanosine)-(2'-O-methyl-ribonucleoside) in mRNA or snRNA + S-adenosyl-L-homocysteine + H+. This activity catalyzes the methylation of the ribose on the first transcribed nucleotide of mRNAs and snRNAs. molecular_function GO:0004483 EC:2.1.1.57 mRNA (nucleoside-2'-O-)-methyltransferase activity Reactome:R-HSA-9694499 Reactome:R-HSA-9923097 RHEA:60860 S-adenosyl-L-methionine:mRNA (nucleoside-2'-O-)-methyltransferase activity MetaCyc:2.1.1.57-RXN mRNA (adenosine-2'-O-)-methyltransferase activity RHEA:19617 RHEA:60864 O-methyltransferase activity RNA methyltransferase activity