Linked Life Data

10833353

Source:http://linkedlifedata.com/resource/pubmed/id/10833353

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2000-7-24
pubmed:abstractText
We propose a simple mathematical model of liver S -adenosylmethionine (AdoMet) metabolism. Analysis of the model has shown that AdoMet metabolism can operate under two different modes. The first, with low metabolic rate and low AdoMet concentration, serves predominantly to supply the cell with AdoMet, the substrate for various cellular methylation reactions. The second, with high metabolic rate and high AdoMet concentration, provides an avenue for cleavage of excess methionine and can serve as a source of cysteine when its increased synthesis is necessary. The switch that triggers interconversion between the "low" and "high" modes is methionine concentration. Under a certain set of parameters both modes may coexist. This behavior results from the kinetic properties of (i) the two isoenzymes of AdoMet synthetase, MATI and MATIII, that catalyse AdoMet production; one is inhibited by AdoMet, whereas the other is activated by it, and (ii) glycine- N -methyltransferase that displays highly cooperative kinetics that is different from that of other AdoMet-dependent methyltransferases. Thus, the model provides an explanation for how different cellular needs are met by regulation of this pathway. The model also correctly identifies a critical role for glycine N -methyltransferase in depleting excess methionine in the high mode, thus avoiding the toxicity associated with elevated levels of this essential amino acid.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0022-5193
pubmed:author
pubmed:copyrightInfo
Copyright 2000 Academic Press.
pubmed:issnType
Print
pubmed:day
21
pubmed:volume
204
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
521-32
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
A substrate switch: a new mode of regulation in the methionine metabolic pathway.
pubmed:affiliation
National Research Center for Hematology, Moscow, 125167, Russia.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.