In enzymology, a mRNA (2'-O-methyladenosine-N<sup>6</sup>-)-methyltransferase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are S-adenosyl methionine and m<sup>7</sup>G(5')pppAm, whereas its two products are S-adenosylhomocysteine and m<sup>7</sup>G(5')pppm<sup>6</sup>Am (mRNA containing an N<sup>6</sup>,2'-O-dimethyladenosine cap).
This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. The systematic name of this enzyme class is S-adenosyl-L-methionine:mRNA (2'-O-methyladenosine-N<sup>6</sup>-)-methyltransferase. Other names in common use include messenger ribonucleate 2'-O-methyladenosine NG-methyltransferase, S-adenosyl-L-methionine:mRNA, and (2'-O-methyladenosine-6-N-)-methyltransferase.