mRNA Cap 2´-O-Methyltransferase adds a methyl group at the 2´-O position of the first nucleotide adjacent to the cap structure at the 5´ end of the RNA

The cap-1 structure has been reported to enhance mRNA translation efficiency and hence may help improve expression in mRNA transfection and microinjection experiments. mRNA Cap 2´-O-Methyltransferase specifically requires RNA with an m7GpppN cap as substrate. It cannot utilize RNA with pN, ppN, pppN or GpppN at the 5´ end. Capped RNA may be prepared via in vitro transcription using cap analog or through enzymatic capping using the Vaccinia Capping Enzyme.

The enzyme utilizes S-adenosylmethionine (SAM) as a methyl donor to methylate capped RNA (cap-0) resulting in a cap-1 structure.