Methyltransferase-like protein 11A, also known as METTL11A, is a member of the methyltransferase superfamily and METTL11 family. Methyltransferase is a type of transferase enzyme which transfers a methyl group from a donor to an acceptor. Methylation often occurs on nucleic bases in DNA or amino acids in protein structures. Methyltransferase uses a reactive methyl group bound to sulfur in S-adenosyl methionine (SAM) as the methyl donor. DNA methylation is often utilized to silence and regulate genes without changing the original DNA sequence. This methylation occurs on cytosine residues. DNA methylation may be necessary for normal growth from embryonic stages in mammals. Methylation can serve to protect DNA from enzymatic cleavage since restriction enzymes are unable to bind and recognize externally modified sequences. This is especially useful in bacterial restriction-modification systems which use restriction enzymes to cleave foreign DNA while keeping their DNA protected by methylation. Methylation of amino acids in the formation of proteins leads to more diversity of possible amino acids and therefore more diversity of function. The methylation reaction occurs on nitrogen atoms either on the N terminus or side-chain position of the protein and is usually irreversible.