Methylenetetrahydrofolate reductase

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5,10-methylenetetrahydrofolate reductase (NADPH)
Image:MTHFR active site.jpg
Ribbon diagram of the active site of E. coli MTHFR. The flavin cofactor (top) is shown interacting with the bound substrate NADH. Image drawn from PDB 1ZPT
Identifiers
Symbol(s)	MTHFR;
External IDs	OMIM: 607093 MGI: 106639 Homologene: 4349
Gene ontology Molecular Function: • methylenetetrahydrofolate reductase (NADPH) activity • protein binding • oxidoreductase activity Biological Process: • amino acid metabolic process • methionine metabolic process • circulation • methionine biosynthetic process
RNA expression pattern
Image:PBB GE MTHFR 206800 at tn.png Image:PBB GE MTHFR 217071 s at tn.png Image:PBB GE MTHFR 217070 at tn.png More reference expression data
Orthologs
	Human	Mouse
Entrez	4524	17769
Ensembl	ENSG00000177000	ENSMUSG00000029009
Uniprot	P42898	Q3V399
Refseq	NM_005957 (mRNA) NP_005948 (protein)	NM_010840 (mRNA) NP_034970 (protein)
Location	Chr 1: 11.77 - 11.79 Mb	Chr 4: 146.88 - 146.9 Mb
Pubmed search	[1]	[2]

Methylenetetrahydrofolate reductase (MTHFR) is an enzyme (EC 1.5.1.20) that exists in the cytoplasm of cells. MTHFR contains a bound flavin cofactor and uses NAD(P)H as the reducing agent.

MTHFR irreversibly reduces 5,10-methylenetetrahydrofolate (substrate) to 5-methyltetrahydrofolate. 5-Methyltetrahydrofolate is used to convert homocysteine (a potentially-toxic amino acid) to methionine by the enzyme methionine synthase.

Polymorphism and role in disease

There is a common DNA sequence variant (polymorphism) in MTHFR at basepair 677 (a change from a C to a T) that results in a thermolabile enzyme with decreased enzymatic activity. Ten percent of the North American population are homozygous for this polymorphism (the incidence is higher in Mediterranean countries and lower in African-Americans). Individuals of 677TT are predisposed to mild hyperhomocysteinemia (high blood homocysteine levels), because they have less MTHFR available to produce 5-methyltetrahydrofolate (which is used to decrease homocysteine). Low dietary intake of the vitamin folic acid can also cause mild hyperhomocysteinemia. This polymorphism and mild hyperhomocysteinemia are associated with neural tube defects in offspring, arterial and venous thrombosis, and cardiovascular disease. It is interesting to note that 677TT individuals are at a decreased risk for certain leukemias and colon cancer, but only when their dietary intake of folate is high. The MTHFR gene could be one of the factors of overall schizophrenia risk.^[1] Schizophrenic patients having the risk allele (T\T) show more deficiencies in executive function tasks.^[1]

Formula of action

MTHFR = methylenetetrahydrofolate reductase
5,10-CH₂-FH₄ = 5,10-methylene tetrahydrofolate
5-CH₃-FH₄ = 5-methyl tetrahydrofolate
NADPH = reduced form of Nicotinamide adenine dinucleotide phosphate
NADP⁺ = oxidized form of Nicotinamide adenine dinucleotide phosphate

References

• MTHFR and homocysteine, Dr. Stephan Moll, retrieved 28 December 2004.

Further reading

Template:1.5-enzyme-stub

v • d • e Protein: flavoproteins
Acetolactate synthase - Acyl CoA dehydrogenase - Apoptosis-inducing factor - Butyryl CoA dehydrogenase - Cryptochrome - Cytochrome b5 reductase - Dihydrolipoamide dehydrogenase - Flavodoxin - Methemoglobin reductase - Methylenetetrahydrofolate reductase - NADH dehydrogenase - NADPH oxidase - Nitrate reductase - Sarcosine oxidase - Thioredoxin reductase

v • d • e CH-NH oxidoreductases (EC 1.5)
1.5.1 - NAD or NADP acceptor	Dihydrofolate reductase - Saccharopine dehydrogenase - Methylenetetrahydrofolate reductase
1.5.3 - oxygen acceptor	Dihydrobenzophenanthridine oxidase - Sarcosine oxidase
1.5.5 - quinone acceptor	Electron-transferring-flavoprotein dehydrogenase

he:MTHFR (אנזים)

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Acknowledgement and Attribution Regarding Sources of Content

Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .