Link to this page
Human Interaction Network Ontology
| Preferred Name | Methylation | |
| Synonyms |
|
|
| Definitions |
Authored: Jassal, B, 2005-02-03 14:13:47 Edited: Jassal, B, 2008-05-19 12:57:01 Methylation is a common but minor pathway of Phase II conjugation compared to glucuronidation or sulfonation. The cofactor used in methylation conjugation is S-adenosylmethionine (SAM). SAM is the second most widely used enzyme substrate after ATP and is involved in a wide range of important biological processes. SAM is sythesized from methionine's reaction with ATP, catalyzed by methionine adenosyltransferase (MAT). There are two genes, MAT1A and MAT2A, which encode for two homologous MAT catalytic subunits, 1 and 2.<br>During conjugation with nucleophilic substrates, the methyl group attached to the sulfonium ion of SAM is transferred to the substrate forming the conjugate. SAM, having lost the methyl moiety, is converted to S-adenosylhomocysteine (SAH). SAH can be hydrolyzed to form adenosine and homocysteine. Homocysteine can either be converted to glutathione or methylated to form methionine, thus forming the starting point for SAM synthesis and completing the cycle.<br>Fuctional groups attacked are phenols, catechols, aliphatic and aromatic amines and sulfhydryl-containing groups. The enzymes that catalyze the transfer of the methyl group to these functional groups are the methyltransferases (MT). MTs are small, cytosolic, monomeric enzymes that utilize SAM as a methyl donor. There are many MTs but the best studied ones are named on the basis of their prototypical substrates: <i><b>COMT</b> (catechol O-methyltransferase)</i>, <i><b>TPMT</b> (thiopurine methyltransferase)</i>, <i><b>TMT</b> (thiol methyltransferase)</i>, <i><b>HNMT</b> (histamine N-methyltransferase)</i> and <i><b>NNMT</b> (nicotinamide N-methyltransferase)</i>. An example of each enzyme mentioned is given. In each case, a typical substrate for the enzyme is shown. |
|
| ID |
http://purl.obolibrary.org/obo/HINO_0016335 |
|
| comment |
Authored: Jassal, B, 2005-02-03 14:13:47 Edited: Jassal, B, 2008-05-19 12:57:01 Methylation is a common but minor pathway of Phase II conjugation compared to glucuronidation or sulfonation. The cofactor used in methylation conjugation is S-adenosylmethionine (SAM). SAM is the second most widely used enzyme substrate after ATP and is involved in a wide range of important biological processes. SAM is sythesized from methionine's reaction with ATP, catalyzed by methionine adenosyltransferase (MAT). There are two genes, MAT1A and MAT2A, which encode for two homologous MAT catalytic subunits, 1 and 2.<br>During conjugation with nucleophilic substrates, the methyl group attached to the sulfonium ion of SAM is transferred to the substrate forming the conjugate. SAM, having lost the methyl moiety, is converted to S-adenosylhomocysteine (SAH). SAH can be hydrolyzed to form adenosine and homocysteine. Homocysteine can either be converted to glutathione or methylated to form methionine, thus forming the starting point for SAM synthesis and completing the cycle.<br>Fuctional groups attacked are phenols, catechols, aliphatic and aromatic amines and sulfhydryl-containing groups. The enzymes that catalyze the transfer of the methyl group to these functional groups are the methyltransferases (MT). MTs are small, cytosolic, monomeric enzymes that utilize SAM as a methyl donor. There are many MTs but the best studied ones are named on the basis of their prototypical substrates: <i><b>COMT</b> (catechol O-methyltransferase)</i>, <i><b>TPMT</b> (thiopurine methyltransferase)</i>, <i><b>TMT</b> (thiol methyltransferase)</i>, <i><b>HNMT</b> (histamine N-methyltransferase)</i> and <i><b>NNMT</b> (nicotinamide N-methyltransferase)</i>. An example of each enzyme mentioned is given. In each case, a typical substrate for the enzyme is shown.
|
|
| definition source |
Reactome, http://www.reactome.org Pubmed15130560 Pubmed10331075 Pubmed10898761
|
|
| label |
Methylation
|
|
| located_in | ||
| prefixIRI |
HINO:0016335
|
|
| prefLabel |
Methylation
|
|
| seeAlso |
ReactomeREACT_6946 GENE ONTOLOGYGO:0032259 Reactome Database ID Release 43156581
|
|
| subClassOf | ||
| has_part |
http://purl.obolibrary.org/obo/HINO_0025109 http://purl.obolibrary.org/obo/HINO_0025108 http://purl.obolibrary.org/obo/HINO_0024196 http://purl.obolibrary.org/obo/HINO_0024194 http://purl.obolibrary.org/obo/HINO_0024232 http://purl.obolibrary.org/obo/HINO_0025111 |
| Delete | Subject | Author | Type | Created |
|---|---|---|---|---|
| No notes to display |