Catalysis of the reaction: an adenosine in mRNA + S-adenosyl-L-methionine = an N(6)-methyladenosine in mRNA + H+ + S-adenosyl-L-homocysteine. This activity is the methylation of adenines in mRNA with the consensus sequence RRACH, where R is a purine, and H is C, A, or U.
Synonyms:
exact_synonym:
mRNA (N6-adenosine)-methyltransferase activity
xref:
EC:2.1.1.348; MetaCyc:RXN-19346; RHEA:55584; reactome:R-HSA-72095 "Internal Methylation of mRNA"