DNA methyltransferases (DNMTs)

DNA methyltransferases (DNMTs)，including DNMT1, DNMT3a and DNMT3b， are a family of enzymes that catalyze the addition of methyl groups onto DNA. DNMT1 acts as the primary maintenance methyltransferase to keep the methylation of DNA that is already established at the genome, whereas DNMT3a and DNMT3b are classified asde novo methyltransferases to reversibly methylate unmethylated DNA. The mechanism of action for DNA methyltransferases (DNMTs) involves the transfer of a methyl group from S-adenosyl methionine (SAM) to the target DNA.