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 []. 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 [].RlmF methylates the adenine in position 1618 of 23S rRNA []. 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 [].
