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Thyroid hormone turnover C

Unless otherwise stated all data on this page refer to the human proteins. Gene information is provided for human (Hs), mouse (Mm) and rat (Rn).


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The thyroid hormones triiodothyronine and thyroxine, usually abbreviated as triiodothyronine and T4, respectively, are synthesized in the thyroid gland by sequential metabolism of tyrosine residues in the glycosylated homodimeric protein thyroglobulin (TG, P01266) under the influence of the haem-containing protein iodide peroxidase. Iodide peroxidase/TPO is a haem-containing enzyme, from the same structural family as eosinophil peroxidase (EPX, P11678), lactoperoxidase (LPO, P22079) and myeloperoxidase (MPO, P05164). Circulating thyroid hormone is bound to thyroxine-binding globulin (SERPINA7, P05543).

Tissue deiodinases

These are 1 TM selenoproteins that remove an iodine from T4 (3,3’,5,5’-tetraiodothyronine) to generate triiodothyronine (3,3’,5-triiodothyronine, a more potent agonist at thyroid hormone receptors) or rT3 (rT3, 3,3’,5’-triiodothyronine, a relatively inactive analogue). DIO1 is also able to deiodinate RT3 to form 3,3’-diidothyronine (T2). Iodotyrosine deiodinase is a 1TM homodimeric enzyme.


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TPO (thyroid peroxidase) C Show summary » More detailed page go icon to follow link

DIO1 (iodothyronine deiodinase 1) C Show summary »

DIO2 (iodothyronine deiodinase 2) C Show summary »

Target Id 2482
Nomenclature iodothyronine deiodinase 2
Common abbreviation DIO2
Previous and unofficial names DIOII | deiodinase | deiodinase, iodothyronine, type II | deiodinase, iodothyronine type II
Genes DIO2 (Hs), Dio2 (Mm), Dio2 (Rn)
Ensembl ID ENSG00000211448 (Hs), ENSMUSG00000007682 (Mm), ENSRNOG00000003894 (Rn)
UniProtKB AC Q92813 (Hs), Q9Z1Y9 (Mm), P70551 (Rn)
EC number T4 -> triiodothyronine
rT3 -> T2

DIO3 (iodothyronine deiodinase 3) C Show summary »

IYD (iodotyrosine deiodinase) C Show summary »

Further reading

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How to cite this family page

Database page citation:

Thyroid hormone turnover. Accessed on 24/05/2022. IUPHAR/BPS Guide to PHARMACOLOGY,

Concise Guide to PHARMACOLOGY citation:

Alexander SPH, Fabbro D, Kelly E, Mathie A, Peters JA, Veale EL, Armstrong JF, Faccenda E, Harding SD, Pawson AJ, Sharman JL, Southan C, Davies JA; CGTP Collaborators. (2019) The Concise Guide to PHARMACOLOGY 2019/20: Enzymes. Br J Pharmacol. 176 Issue S1: S297-S396.