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unreviewed

Methionine synthase (MTR)

2 reactions · 2 pathways

Cofactors used

Cobalamin (B12) · B12 (Cobalamin) THF (folate) · B9 (Folate)

Clinical / pharmacological. B12-dependent; deficiency causes megaloblastic anaemia and the methyl-folate trap

What it does, reaction by reaction

2 reactions

Methionine Cycle / Transmethylation (SAM Cycle, homocysteine) Amino Acid & Nitrogen Metabolism · Cytosol

step 4 Irreversible/directional

Homocysteine + 5-methyl-THF → methionine + THF

Converts Homocysteine 5-Methyl-THF into Methionine Tetrahydrofolate (THF)

› Notes

Methionine synthase (MTR) requires methylcobalamin (vitamin B12) and links the methionine cycle to the folate cycle. Reductive reactivation of oxidized cobalamin requires methionine synthase reductase, NADPH, FAD, FMN, and SAM; remethylation is the principal methionine-conserving route in most tissues.

One-Carbon Metabolism (Folate Cycle) Amino Acid & Nitrogen Metabolism · Cytosol + mitochondrion

step 10 Irreversible/directional

5-Methyl-THF + homocysteine → THF + methionine

Converts 5-Methyl-THF Homocysteine into Tetrahydrofolate (THF) Methionine

› Notes

Methionine synthase (5-methyltetrahydrofolate–homocysteine methyltransferase) requires methylcobalamin (vitamin B12) and transfers the methyl group through a cobalamin intermediate. The reaction regenerates THF and prevents trapping of cellular folate as 5-methyl-THF.

Showing all 2 reactions.

What accelerates and inhibits it

Regulation is pathway-specific, so each context is listed separately

1 entries

Methionine Cycle / Transmethylation (SAM Cycle, homocysteine)

Listed there as: Methionine synthase

Accelerated by

5-methyl-THF, homocysteine, and functional B12 availability

Inhibited by

B12 deficiency/inactivation; nitrous oxide oxidizes cobalamin and inhibits function

Hormonal control

Mainly controlled by vitamin status and substrate flux

Recent literature

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Europe PMC · from cache · sorted by publication date

  1. 1
    Lessons learned from the deployment of oral cholera vaccine by maintaining the controlled temperature chain (CTC) in an urban setting, Bangladesh.

    Islam MT, Khan AI, Khan ZH, Amin MA, Shahnaz S, Sultana QF, Bhuiyan MTR, Rimal A, Robertson J, Kahn AL, Qadri… · 2026-07-23

    unreviewed
  2. 2
    Leveraging global tools for adolescent and youth health planning and programming: process and lessons learnt from Madagascar.

    Ngabonzima A, Keogh SC, Guthold R, Lydia Yasmine L, Bisoborwa GK, Andrianasolo S, Siga Diane Niane E, Ye M, R… · 2026-03-26

    open access unreviewed
  3. 3
    Riboflavin intake and kidney health: population evidence and mechanistic insights from NHANES and molecular docking analyses.

    Wu P, Long W, Xiao X, Wang L, Xu Y, Ma X. · 2026-01-25

    cited 1× open access unreviewed
  4. 4
    Optimizing saturation time for maximum CEST contrast.

    Zhao Y, Chung JJ, Jin T. · 2026-07-13

    unreviewed
  5. 5
    Methionine restriction plus vitamin B12 antagonism overcomes methionine independence for cancer therapy.

    Lacombe V, Aurrière J, Mellinger A, Khiati S, Giachetti N, Bessaguet F, Bellal S, Reynier P, Geneviève F, Urb… · 2026-07-09

    unreviewed
  6. 6
    Industrial red mud establishes redox-active interfaces to steer metabolic pathways toward chain elongation in sludge anaerobic fermentation.

    Cai Q, He J, Qiu W, Wang Y, Fang K, Zou X, Aili A, Zhong Y, Pan X. · 2026-06-11

    unreviewed
  7. 7
    Proteome-informed interrogation of a methanogenic archaeon links stress response mechanisms with microbial performance and robustness during biomethanation.

    Ale Enriquez F, Callister SJ, Nelson WC, Kim DN, Nicora CD, Chu RK, Delgado D, Ahring BK. · 2026-06-05

    unreviewed
  8. 8
    Genome mining of Neowestiellopsis persica NC-DW uncovers cryptic antimicrobial gene clusters with potential against drug-resistant pathogens.

    Lamare DW, Nongbri DL, Aguan K, Chaurasia N. · 2026-06-25

    unreviewed
  9. 9
    Characterization of a novel mosaic-like mtr operon and inter-regional transmission of dual-resistant Neisseria gonorrhoeae ST7363 sub-lineage in China.

    Zhu B, Wang D, Zhang C, Yang Y, Gan Q, Huang Y, Gu W, Peng J. · 2026-05-25

    unreviewed
  10. 10
    Optimization of mode of heat treatment for thermoluminescence properties of beta irradiated synthetic quartz.

    Kale YD, Akhani TB, Mahepal NK, Solanki MB, Gandhi YH. · 2026-04-30

    unreviewed

External claims. These come from an index outside this database and are not checked against it. Treat them as leads.