(1,2) It is formed in vivo from the reaction of the amino acid methionine and adenosine triphosphate (ATP), catalyzed by the enzyme methionine adenosyltransferase
. Following the donation of a methyl group, SAM-e is converted to S-adenosyl-homocysteine, (3) which is further broken down to adenosine and homocysteine.
In the first two sections, biochemists, gastroenterologists, and other specialists from the US, Israel, and Europe discuss fatty liver vulnerability to hypoxic and inflammatory stress, hepatocellular carcinoma, cellular stress responses in the regulation of drug-induced liver steatosis, the role of the Keapl/Nrf2 pathway, the role of methionine adenosyltransferase
genes in liver health and disease, the role and modulation of nitric oxide in the cirrhotic liver, and the role of mitochondria in alcoholic and nonalcoholic fatty liver disease.
Role of methionine adenosyltransferase and S-adenosylmethionine in alcohol-associated liver cancer.
Changes in the expression of methionine adenosyltransferase genes and S-adenosylmethionine homeostasis during hepatic stellate cell activation.
Distal motor axonopathy and central nervous system myelin vacuolation caused by cycloleucine, an inhibitor of methionine adenosyltransferase
. Brain 1992; 115:935-55.
Methionine, in turn, is an essential amino acid that, together with ATP, participates in the formation of SAMe, in a reaction catalyzed by methionine adenosyltransferase
Between the two isoforms of methionine adenosyltransferase
, MAT-I is inhibited and MET-III is activated by its product, AdoMet (; ).
Methionine can also be increased in methionine adenosyltransferase
I/III deficiency, S-adenosylmethionine hydrolase deficiency, glycine N-methyltransferase deficiency, generalized liver disease, and infants fed a formula rich in methionine.
The effects of L-Dopa on the activity of methionine adenosyltransferase
: relevance to L-Dopa therapy and tolerance.
Methionine is converted to SAM by methionine adenosyltransferase
(EC 220.127.116.11) in the presence of ATP.
Methionine is converted to S-adenosylmethionine (SAM), the major intracellular methyl donor, by methionine adenosyltransferase
(EC 18.104.22.168) and subsequently to S-adenosylhomocysteine (SAH) by a variety of cellular methyltransferases present in all cells.
One enzyme class in particular, the methionine adenosyltransferases
(MAT), in 1983 was found to be reduced in the blood cells of depressed patients, yet elevated in patients in the manic phase.