Methyltransferase Like Protein 3 (METTL3)

The methylation of internal adenosine residues in eukaryotic mRNA, forming N6-methyladenosine (m6A), is catalyzed by a complex multicomponent enzyme, of which METTL3 is the critical S-adenosyl-L-methionine-binding subunit.

The deduced 580-amino acid protein has a calculated molecular mass of 65 kD, close to the purification product molecular mass of 70 kD. METTL3 contains 2 putative nuclear localization signals and 2 consensus methylation motifs. Northern blot analysis detected 2.0-kb and 3.0-kb transcripts in all tissues examined. METTL3 shares 54% amino acid identity with the C-terminal half of S. cerevisiae Spo8, which was subsequently renamed Ime4. Immunofluorescnce localized METTL3 to speckles in interphase HeLa cell nuclei.