title: S-adenosylmethionine synthesis: molecular mechanisms and clinical implications.
abstract: Methionine adenosyltransferase (MAT) is an ubiquitous enzyme that catalyzes the synthesis of S-adenosylmethionine from methionine and ATP. In mammals, there are two genes coding for MAT, one expressed exclusively in the liver and a second enzyme present in all tissues. Molecular studies indicate that liver MAT exists in two forms: as a homodimer and as a homotetramer of the same oligomeric subunit. The liver-specific isoenzymes are inhibited in human liver cirrhosis, and this is the cause of the abnormal metabolism of methionine in these subjects.
authors.affiliation: Instituto de Investigaciones Biomédicas, CSIC, Madrid, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: Mato
authors.forename: L
authors.initials: L
authors.lastname: Alvarez
authors.forename: P
authors.initials: P
authors.lastname: Ortiz
authors.forename: M A
authors.initials: MA
authors.lastname: Pajares
mesh_terms: D000818:Animals; D056486:Chemical and Drug Induced Liver Injury; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D006801:Humans; D008099:Liver / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D008107:Liver Diseases / Q000378:metabolism / Q000517:prevention & control; D008715:Methionine / Q000378:metabolism; D008716:Methionine Adenosyltransferase / Q000737:chemistry / Q000172:deficiency / Q000235:genetics*; D008745:Methylation; D012436:S-Adenosylmethionine / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D013045:Species Specificity
chemical_list: D012436:S-Adenosylmethionine; D008715:Methionine; D008716:Methionine Adenosyltransferase