5-Methyltetrahydrofolate-homocysteine methyltransferase 2941863 224262791 2008-07-08T01:37:10Z ProteinBoxBot 3991663 Replaced protein Box Template with PBB Template for easy viewing. {{PBB|geneid=4548}} '''5-methyltetrahydrofolate-homocysteine methyltransferase''', also known as '''MTR''', is a human [[gene]].<ref name="entrez">{{cite web | title = Entrez Gene: MTR 5-methyltetrahydrofolate-homocysteine methyltransferase| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=4548| accessdate = }}</ref> <!-- The PBB_Summary template is automatically maintained by Protein Box Bot. See Template:PBB_Controls to Stop updates. --> {{PBB_Summary | section_title = | summary_text = MTR encodes the enzyme 5-methyltetrahydrofolate-homocysteine methyltransferase. This enzyme, also known as cobalamin-dependent methionine synthase, catalyzes the final step in methionine biosynthesis. Mutations in MTR have been identified as the underlying cause of methylcobalamin deficiency complementation group G.<ref name="entrez">{{cite web | title = Entrez Gene: MTR 5-methyltetrahydrofolate-homocysteine methyltransferase| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=4548| accessdate = }}</ref> }} '''5-Methyltetrahydrofolate-homocysteine methyltransferase''' or ('''MTR''') is an [[enzyme]] responsible for the production of [[methionine]] from [[homocysteine]]. MTR forms part of the [[S-adenosyl methionine]] cycle and is also called methionine synthase.<ref>{{cite journal |author=Banerjee RV, Matthews RG |title=Cobalamin-dependent methionine synthase |journal=FASEB J. |volume=4 |issue=5 |pages=1450–9 |year=1990 |pmid=2407589 |url=http://www.fasebj.org/cgi/reprint/4/5/1450.pdf}}</ref> ==Function== '''MTR''' contains the cofactor - [[methylcobalamin]] ([[methylcobalamin|MeB<sub><small>12</small></sub>]]) and uses the substrates [[Tetrahydrofolate|N5-methyl-tetrahydrofolate]] ([[Tetrahydrofolate|N<sup><small>5</small></sup>-methyl-THF]]) and [[homocysteine]]. The enzyme works in two steps in a [[enzyme kinetics|ping-pong reaction]]. First, methylcobalamin is formed by a methyl group transfer from N<sup><small>5</small></sup>-mTHF with formation of MeB<sub><small>12</small></sub> and [[tetrahydrofolate]] ([[Tetrahydrofolate|THF]]). In the second step, MeB<sub><small>12</small></sub> transfers this methyl group to ([[homocysteine]]), regenerating the cofactor [[cobalamin]] and releasing the product [[methionine]] [[Image:VitaminB12_2.png|thumb|left|400px|The MTR reaction]] <br clear="all" /> ==See also== * [[methyltransferase]] * [[Arakawa's syndrome II]] * [[5-methyltetrahydrofolate]] ==References== {{reflist}} ==Further reading== {{refbegin | 2}} {{PBB_Further_reading | citations = *{{cite journal | author=Banerjee RV, Matthews RG |title=Cobalamin-dependent methionine synthase. |journal=FASEB J. |volume=4 |issue= 5 |pages= 1450–9 |year= 1990 |pmid= 2407589 |doi= }} *{{cite journal | author=Ludwig ML, Matthews RG |title=Structure-based perspectives on B12-dependent enzymes. |journal=Annu. Rev. Biochem. |volume=66 |issue= |pages= 269–313 |year= 1997 |pmid= 9242908 |doi= 10.1146/annurev.biochem.66.1.269 }} *{{cite journal | author=Matthews RG, Sheppard C, Goulding C |title=Methylenetetrahydrofolate reductase and methionine synthase: biochemistry and molecular biology. |journal=Eur. J. Pediatr. |volume=157 Suppl 2 |issue= |pages= S54–9 |year= 1998 |pmid= 9587027 |doi= }} *{{cite journal | author=Garovic-Kocic V, Rosenblatt DS |title=Methionine auxotrophy in inborn errors of cobalamin metabolism. |journal=Clinical and investigative medicine. Médecine clinique et experimentale |volume=15 |issue= 4 |pages= 395–400 |year= 1992 |pmid= 1516297 |doi= }} *{{cite journal | author=O'Connor DL, Moriarty P, Picciano MF |title=The impact of iron deficiency on the flux of folates within the mammary gland. |journal=International journal for vitamin and nutrition research. Internationale Zeitschrift für Vitamin- und Ernährungsforschung. Journal international de vitaminologie et de nutrition |volume=62 |issue= 2 |pages= 173–80 |year= 1992 |pmid= 1517041 |doi= }} *{{cite journal | author=Everman BW, Koblin DD |title=Aging, chronic administration of ethanol, and acute exposure to nitrous oxide: effects on vitamin B12 and folate status in rats. |journal=Mech. Ageing Dev. |volume=62 |issue= 3 |pages= 229–43 |year= 1992 |pmid= 1583909 |doi= }} *{{cite journal | author=Vassiliadis A, Rosenblatt DS, Cooper BA, Bergeron JJ |title=Lysosomal cobalamin accumulation in fibroblasts from a patient with an inborn error of cobalamin metabolism (cblF complementation group): visualization by electron microscope radioautography. |journal=Exp. Cell Res. |volume=195 |issue= 2 |pages= 295–302 |year= 1991 |pmid= 2070814 |doi= }} *{{cite journal | author=Li YN, Gulati S, Baker PJ, ''et al.'' |title=Cloning, mapping and RNA analysis of the human methionine synthase gene. |journal=Hum. Mol. Genet. |volume=5 |issue= 12 |pages= 1851–8 |year= 1997 |pmid= 8968735 |doi= }} *{{cite journal | author=Gulati S, Baker P, Li YN, ''et al.'' |title=Defects in human methionine synthase in cblG patients. |journal=Hum. Mol. Genet. |volume=5 |issue= 12 |pages= 1859–65 |year= 1997 |pmid= 8968736 |doi= }} *{{cite journal | author=Leclerc D, Campeau E, Goyette P, ''et al.'' |title=Human methionine synthase: cDNA cloning and identification of mutations in patients of the cblG complementation group of folate/cobalamin disorders. |journal=Hum. Mol. Genet. |volume=5 |issue= 12 |pages= 1867–74 |year= 1997 |pmid= 8968737 |doi= }} *{{cite journal | author=Chen LH, Liu ML, Hwang HY, ''et al.'' |title=Human methionine synthase. cDNA cloning, gene localization, and expression. |journal=J. Biol. Chem. |volume=272 |issue= 6 |pages= 3628–34 |year= 1997 |pmid= 9013615 |doi= }} *{{cite journal | author=Wilson A, Leclerc D, Saberi F, ''et al.'' |title=Functionally null mutations in patients with the cblG-variant form of methionine synthase deficiency. |journal=Am. J. Hum. Genet. |volume=63 |issue= 2 |pages= 409–14 |year= 1998 |pmid= 9683607 |doi= }} *{{cite journal | author=Salomon O, Rosenberg N, Zivelin A, ''et al.'' |title=Methionine synthase A2756G and methylenetetrahydrofolate reductase A1298C polymorphisms are not risk factors for idiopathic venous thromboembolism. |journal=Hematol. J. |volume=2 |issue= 1 |pages= 38–41 |year= 2002 |pmid= 11920232 |doi= 10.1038/sj/thj/6200078 }} *{{cite journal | author=Watkins D, Ru M, Hwang HY, ''et al.'' |title=Hyperhomocysteinemia due to methionine synthase deficiency, cblG: structure of the MTR gene, genotype diversity, and recognition of a common mutation, P1173L. |journal=Am. J. Hum. Genet. |volume=71 |issue= 1 |pages= 143–53 |year= 2002 |pmid= 12068375 |doi= }} *{{cite journal | author=De Marco P, Calevo MG, Moroni A, ''et al.'' |title=Study of MTHFR and MS polymorphisms as risk factors for NTD in the Italian population. |journal=J. Hum. Genet. |volume=47 |issue= 6 |pages= 319–24 |year= 2002 |pmid= 12111380 |doi= 10.1007/s100380200043 }} *{{cite journal | author=Doolin MT, Barbaux S, McDonnell M, ''et al.'' |title=Maternal genetic effects, exerted by genes involved in homocysteine remethylation, influence the risk of spina bifida. |journal=Am. J. Hum. Genet. |volume=71 |issue= 5 |pages= 1222–6 |year= 2003 |pmid= 12375236 |doi= }} *{{cite journal | author=Zhu H, Wicker NJ, Shaw GM, ''et al.'' |title=Homocysteine remethylation enzyme polymorphisms and increased risks for neural tube defects. |journal=Mol. Genet. Metab. |volume=78 |issue= 3 |pages= 216–21 |year= 2004 |pmid= 12649067 |doi= }} }} {{refend}} ==External links== * [http://www.expasy.org/cgi-bin/enzyme-search-ec ENZYME: EC 2.1.1.13] * {{MeshName|5-Methyltetrahydrofolate-Homocysteine+S-Methyltransferase}} {{transferase-stub}} {{Methyltransferases}} {{Amino acid metabolism enzymes}} [[Category:Enzymes]] [[Category:EC 2.1.1]] [[he:מתיונין סינתאז]] [[pl:Metylotransferaza homocysteinowa]] <!-- The PBB_Controls template provides controls for Protein Box Bot, please see Template:PBB_Controls for details. --> {{PBB_Controls | update_page = yes | require_manual_inspection = no | update_protein_box = yes | update_summary = yes | update_citations = yes }}