InterPro domain: IPR010286

This family includes ribosomal RNA large subunit methyltransferase F (RlmF), and related proteins, including methyltransferase-like protein 16 (METTL16). METTL16 is a conserved RNA methyltransferase which interacts specifically with the MALAT1 triple helix. METTL16 shows nuclear localisation [ 1 ]. Another functional study indicates that METTL16 regulates expression of human MAT2A, which encodes the SAM synthetase expressed in most cells. Furthermore, results indicate that METTL16 is the long-unknown methyltransferase for the U6 spliceosomal small nuclear RNA (snRNA) and it has evolved an additional function in vertebrates to control SAM homeostasis by post-transcriptionally regulating SAM synthetase gene expression [ 2 ].

RlmF methylates the adenine in position 1618 of 23S rRNA [ 3 ]. This family also includes psilocybin synthase (PsiM), which is a methyltransferase involved in the biosynthesis of the psychotropic agent psilocybin from the mushroom Psilocybe cubensis [ 4 ].

1. Methyltransferase-like protein 16 binds the 3'-terminal triple helix of MALAT1 long noncoding RNA. Proc. Natl. Acad. Sci. U.S.A. 113, 14013-14018
2. The U6 snRNA m6A Methyltransferase METTL16 Regulates SAM Synthetase Intron Retention. Cell 169, 824-835.e14
3. The ybiN gene of Escherichia coli encodes adenine-N6 methyltransferase specific for modification of A1618 of 23 S ribosomal RNA, a methylated residue located close to the ribosomal exit tunnel. J. Mol. Biol. 375, 291-300
4. Enzymatic Synthesis of Psilocybin. Angew. Chem. Int. Ed. Engl. 56, 12352-12355