S-Adenosyl methionine[alternative names 1] is a common cosubstrate involved in methyl group transfers, transsulfuration, and aminopropylation. Although these anabolic reactions occur throughout the body, most SAM-e is produced and consumed in the liver. More than 40 methyl transfers from SAM-e are known, to various substrates such as nucleic acids, proteins, lipids and secondary metabolites. It is made from adenosine triphosphate (ATP) and methionine by methionine adenosyltransferase (EC 2.5.1.6). SAM was first discovered in Italy by Giulio Cantoni in 1952. In bacteria, SAM-e is bound by the SAM riboswitch, which regulates genes involved in methionine or cysteine biosynthesis.