SAM is sythesized from methionine's reaction with ATP Authored: Gopinathrao, G, 2008-05-21 15:52:50 EC Number: 2.5.1.6 Edited: Gopinathrao, G, 2006-04-27 13:13:48 Pubmed12163696 Pubmed9175157 Reactome Database ID Release 43174391 Reactome, http://www.reactome.org ReactomeREACT_6819 Reviewed: D'Eustachio, P, 2008-06-12 14:43:38 S-adenosylmethionine (SAM) is an essential metabolite in all cells. SAM is a precursor in the synthesis of polyamines. Methionine adenosyltransferase (MAT; EC 2.5.1.6) catalyzes the only known SAM biosynthetic reaction from methionine and ATP. In mammalian tissues, three different forms of MAT (MAT I, MAT III and MAT II) have been identified that are the product of two different genes (MAT1A and MAT2A). A third gene MAT2B has been identified and is known to be a part of MAT II heterotetramer complex.