Catalytic subunit of the N6-methyltransferase complex, a multiprotein complex that mediates N6-methyladenosine (m6A) methylation at the 5'-[AG]GAC-3' consensus sites of some mRNAs (PubMed:18505803, PubMed:28503769). Associates with MTB, FIP37, VIR and HAKAI to form the m6A writer complex which is essential for adenosine methylation at specific mRNA sequences (PubMed:28503769). N6-methyladenosine (m6A) plays a role in mRNA stability, processing, translation efficiency and editing (PubMed:18505803, PubMed:28503769). an adenosine in mRNA + S-adenosyl-L-methionine = an N(6)-methyladenosine in mRNA + H(+) + S-adenosyl-L-homocysteine Interacts with FIP37 (PubMed:18505803, PubMed:28503769). Interacts with MTB (PubMed:28503769). Associates with MTB, FIP37, VIR and HAKAI to form the m6A writer complex which is essential for adenosine methylation at specific mRNA sequences (PubMed:28503769). Embryonic lethality: arrest at the globular stage of embryo development (PubMed:15266054, PubMed:18505803). Arrested seeds are deficient in mRNAs containing N6-methyladenosine (m6A) (PubMed:18505803). Belongs to the MT-A70-like family.