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A reference for what the literature reports. Not medical advice.

© 2026 CatalystPrivacy TermsReference data under the licences listed on the attribution page.

Proteins/UNIPROT:P31513

FMO3

Protein·UNIPROT:P31513Flavin-containing monooxygenase 3

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Essential hepatic enzyme that catalyzes the oxygenation of a wide variety of nitrogen- and sulfur-containing compounds including drugs as well as dietary compounds. Plays an important role in the metabolism of trimethylamine (TMA), via the production of trimethylamine N-oxide (TMAO) metabolite. TMA is generated by the action of gut microbiota using dietary precursors such as choline, choline containing compounds, betaine or L-carnitine. By regulating TMAO concentration, FMO3 directly impacts both platelet responsiveness and rate of thrombus formation..

Function from UniProtKB (P31513), read 2026-09-23. CC BY 4.0.

Curated compounds routed: 0

What the reference databases state

Inferred

Inferred — not reported by a source. Evidence key

GenCC submitters' classifications

2 rows

severe primary trimethylaminuria has a germline basis in FMO3DiseaseGenCC HGNC:3771|MONDO:0018767Inferred only
trimethylaminuria has a germline basis in FMO3DiseaseGenCC HGNC:3771|MONDO:0011182Inferred only

Statements

38 statements

38 statements · 8 reference databases · Subject: FMO3 · Sources: Bgee, Hetionet, Human Protein Atlas, Human-GEM, Reactome, Rhea, UniProt, WikiPathways

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BSX covaries with FMO3ProteinHetionet hetionet:covaries:2328-390259Inferred only
CELA1 covaries with FMO3ProteinHetionet hetionet:covaries:1990-2328Inferred only
FMO3 covaries with CELA3BProteinHetionet hetionet:covaries:2328-23436Inferred only
COX6A2 covaries with FMO3ProteinHetionet hetionet:covaries:1339-2328Inferred only
CYP3A4 covaries with FMO3ProteinHetionet hetionet:covaries:1576-2328Inferred only
GAL3ST2 covaries with FMO3ProteinHetionet hetionet:covaries:2328-64090Inferred only
HNRNPA3 covaries with FMO3ProteinHetionet hetionet:covaries:220988-2328Inferred only
RCVRN covaries with FMO3ProteinHetionet hetionet:covaries:2328-5957Inferred only
FMO3 covaries with SPRR1AProteinHetionet hetionet:covaries:2328-6698Inferred only
TIGD7 covaries with FMO3ProteinHetionet hetionet:covaries:2328-91151Inferred only
TMEM200C covaries with FMO3ProteinHetionet hetionet:covaries:2328-645369Inferred only
TMEM230 covaries with FMO3ProteinHetionet hetionet:covaries:2328-29058Inferred only

Show the remaining 26

XKR6 covaries with FMO3ProteinHetionet hetionet:covaries:2328-286046Inferred only
FMO3 is expressed in liverAnatomyBgee ENSG00000007933Inferred only
FMO3 is expressed in liverAnatomyHuman Protein Atlas ENSG00000007933Inferred only
FMO3 is expressed in nasal cavity mucosaAnatomyBgee ENSG00000007933Inferred only
FMO3 is expressed in olfactory segment of nasal mucosaAnatomyBgee ENSG00000007933Inferred only
FMO3 is expressed in right lobe of liverAnatomyBgee ENSG00000007933Inferred only
CEBPB interacts with FMO3ProteinHetionet hetionet:interacts:1051-2328Inferred only
hypotaurine is metabolised by FMO3CompoundRhea RHEA:69819Inferred only
selenomethionine is metabolised by FMO3CompoundHuman-GEM MAR07138Inferred only
selenomethionine is metabolised by FMO3CompoundHuman-GEM MAR04009Inferred only
FMO3 participates in Biological oxidationsPathwayReactome R-HSA-211859Inferred only
FMO3 participates in Catalytic cycle of mammalian flavin containing monooxygenases FMOs PathwayWikiPathways WP688Inferred only
FMO3 participates in Defective FMO3 causes TMAUPathwayReactome R-HSA-5579019Inferred only
FMO3 participates in Diet dependent trimethylamine trimethylamine N oxide metabolism PathwayWikiPathways WP5219Inferred only
FMO3 participates in DiseasePathwayReactome R-HSA-1643685Inferred only
FMO3 participates in Diseases of metabolismPathwayReactome R-HSA-5668914Inferred only
FMO3 participates in FMO oxidises nucleophilesPathwayReactome R-HSA-217271Inferred only
FMO3 participates in Metabolic disorders of biological oxidation enzymesPathwayReactome R-HSA-5579029Inferred only
FMO3 participates in MetabolismPathwayReactome R-HSA-1430728Inferred only
FMO3 participates in Metapathway biotransformation Phase I and IIPathwayWikiPathways WP702Inferred only
FMO3 participates in Nicotine metabolism in liver cellsPathwayWikiPathways WP1600Inferred only
FMO3 participates in Phase I - Functionalization of compoundsPathwayReactome R-HSA-211945Inferred only
FMO3 participates in Sudden infant death syndrome SIDS susceptibility pathwaysPathwayWikiPathways WP706Inferred only
FMO3 participates in Sulindac metabolic pathwayPathwayWikiPathways WP2542Inferred only
FMO3 participates in Tamoxifen metabolismPathwayWikiPathways WP691Inferred only
FMO3 requires the cofactor FAD(3-)CompoundUniProt P31513Inferred only

Reactions

8 reactions

proton+NADPH(4-)+dioxygen+selenomethioninewater+NADP(3-)+MAM02892r
Catalysed by FMO3 or FMO1 or FMO4 or FMO2 or FMO5
Reaction pageLeft to rightBalancedEC 1.14.13.8endoplasmic reticulum
Human-GEM MAR04009CC BY 4.0Reference data
proton+

Other names

7 names

Resolves to: FMO3

Also called: Dimethylaniline monooxygenase [N-oxide-forming] 3Dimethylaniline oxidase 3FMO 3FMO form 2FMO IIHepatic flavin-containing monooxygenase 3Trimethylamine monooxygenase

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+selenomethionine

→

+MAM02892c

Catalysed by FMO3 or FMO1 or FMO4 or FMO2 or FMO5

Reaction pageLeft to rightBalancedEC 1.14.13.8cytosol

Human-GEM MAR07138CC BY 4.0Reference data

NADPH(4-)+dioxygen+MAM03053cwater+NADP(3-)+MAM03054c

Catalysed by FMO3 or FMO1 or FMO4 or FMO2 or FMO5

Reaction pageLeft to rightBalancedEC 1.14.13.8cytosol

Human-GEM MAR09514CC BY 4.0Reference data

CHEBI:16664+NADPH(4-)+dioxygen+hydronCHEBI:16959+NADP(3-)+water

Catalysed by FMO3

Reaction pageLeft to rightBalanced

Rhea RHEA:10796CC BY 4.0Reference data

CHEBI:16269+NADPH(4-)+dioxygen+hydronCHEBI:17735+NADP(3-)+water

Catalysed by FMO4 or FMO3 or FMO5 or FMO1

Reaction pageLeft to rightBalanced

Rhea RHEA:24468CC BY 4.0Reference data

CHEBI:58389+NADPH(4-)+dioxygenCHEBI:15724+NADP(3-)+water

Catalysed by FMO3 or FMO1

Reaction pageLeft to rightBalanced

Rhea RHEA:31979CC BY 4.0Reference data

CHEBI:59806+NADPH(4-)+dioxygenCHEBI:142660+NADP(3-)+water

Catalysed by FMO3

Reaction pageLeft to rightBalanced

Rhea RHEA:58720CC BY 4.0Reference data

hypotaurine+NADPH(4-)+dioxygen+hydrontaurine+NADP(3-)+water

Catalysed by FMO3 or FMO1

Reaction pageLeft to rightBalanced

Rhea RHEA:69819CC BY 4.0Reference data