This entry represents the FAM173 family, including N-lysine methyltransferase FAM173A and FAM173B. FAM173B is a lysine-specific methyltransferase (KMT) responsible for methylation of ATP synthase c-subunit (ATPSc), a key protein in cellular ATP production []. FAM173B, therefore, was renamed ATPSCKMT. It has been shown to promote chronic pain and is involved in persistent inflammatory and neuropathic pain via a pathway dependent on its methyltransferase activity [].