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Proteins/UNIPROT:P55073
Plays a crucial role in the metabolism of thyroid hormones (TH) and has specific roles in TH activation and inactivation by deiodination. Catalyzes the deiodination of L-thyroxine (T4) to 3,3',5'-triiodothyronine (rT3), 3,5,3'-triiodothyronine (T3) to 3,3'-diiodothyronine (3,3'-T2), 3,5-diiodothyronine (3,5-T2) to 3-monoiodothyronine (3-T1), rT3 to 3',5'-diiodothyronine (3',5'-T2) and 3,3'-T2 to 3'-monoiodothyronine (3'-T1) via inner-ring deiodination (IRD). Catalyzes the deiodination of 3-T1 to L-thyronine (T0) via outer-ring deiodination (ORD). Catalyzes the tyrosyl ring deiodinations of 3,3',5,5'-tetraiodothyronamine, 3,3',5'-triiodothyronamine, 3,5,3'-triiodothyronamine, 3,5-diiodothyronamine, 3,3'-diiodothyronamine and 3-iodothyronamine..
Function from UniProtKB (P55073), read 2026-09-23. CC BY 4.0.
Curated compounds routed: 1 · substrate of
1 compound
1 compound.
0 reported routes1 assembled route
90 statements
90 statements · 5 reference databases · Subject: DIO3 · Sources: Hetionet, Human-GEM, Reactome, Rhea, WikiPathways
14 reactions
3,3'-diiodo-L-thyronine+iodide+NADP(3-)NADPH(4-)+3,3',5-triiodo-L-thyronine
Catalysed by DIO3 or DIO2 or DIO1
Reaction pageReversibleBalancedEC 1.21.99.4, 1.21.99.3cytosol
Human-GEM MAR06826CC BY 4.0Reference data
6 names
Resolves to: DIO3
Reaction pageReversibleBalancedEC 1.21.99.4, 1.21.99.3endoplasmic reticulum
Human-GEM MAR06827CC BY 4.0Reference data
3,3',5'-triiodo-L-thyronine+iodide+A+hydronL-thyroxine+AH2
Reaction pageRight to leftBalanced
Rhea RHEA:18897CC BY 4.0Reference data
3,3'-diiodo-L-thyronine+iodide+A+hydron3,3',5-triiodo-L-thyronine+AH2
Reaction pageRight to leftBalanced
Rhea RHEA:82571CC BY 4.0Reference data
3-iodo-L-thyronine+iodide+A+hydron3,5-diiodo-L-thyronine+AH2
Reaction pageRight to leftBalanced
Rhea RHEA:82895CC BY 4.0Reference data
L-thyronine+iodide+A+hydron3-iodo-L-thyronine+AH2
Catalysed by DIO3
Reaction pageRight to leftBalanced
Rhea RHEA:83771CC BY 4.0Reference data
3',5'-diiodo-L-thyronine+iodide+A+hydron3,3',5'-triiodo-L-thyronine+AH2
Catalysed by DIO3
Reaction pageRight to leftBalanced
Rhea RHEA:83775CC BY 4.0Reference data
3'-iodo-L-thyronine+iodide+A+hydron3,3'-diiodo-L-thyronine+AH2
Catalysed by DIO3
Reaction pageRight to leftBalanced
Rhea RHEA:83779CC BY 4.0Reference data
3',5'-diiodothyronamine+iodide+A+hydron3,3',5'-triiodothyronamine+AH2
Catalysed by DIO3
Reaction pageRight to leftBalanced
Rhea RHEA:83799CC BY 4.0Reference data
3,3',5'-triiodothyronamine+iodide+A+hydron3,3',5,5'-tetraiodothyronamine+AH2
Catalysed by DIO3
Reaction pageRight to leftBalanced
Rhea RHEA:83807CC BY 4.0Reference data
3,3'-diiodothyronamine+iodide+A+hydron3,3',5-triiodothyronamine+AH2
Reaction pageRight to leftBalanced
Rhea RHEA:83811CC BY 4.0Reference data
3'-iodothyronamine+iodide+A+hydron3,3'-diiodothyronamine+AH2
Catalysed by DIO3
Reaction pageRight to leftBalanced
Rhea RHEA:83815CC BY 4.0Reference data