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Deiodinase
From Wikipedia, the free encyclopedia
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deiodinase, iodothyronine, type I
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| Identifiers | |
| Symbol | DIO1 TXDI1 |
| HUGO | 2883 |
| Entrez | 1733 |
| OMIM | 147892 |
| RefSeq | NM_000792 |
| UniProt | P49895 |
| Other data | |
| EC number | 1.97.1.10 |
| Locus | Chr. 1 p32-p33 |
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deiodinase, iodothyronine, type II
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| Identifiers | |
| Symbol | DIO2 |
| HUGO | 2884 |
| Entrez | 1734 |
| OMIM | 601413 |
| RefSeq | NM_000793 |
| UniProt | Q92813 |
| Other data | |
| Locus | Chr. 14 q24.2-24.3 |
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deiodinase, iodothyronine, type III
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| Identifiers | |
| Symbol | DIO3 TXDI3 |
| HUGO | 2885 |
| Entrez | 1735 |
| OMIM | 601038 |
| RefSeq | NM_001362 |
| UniProt | P55073 |
| Other data | |
| Locus | Chr. 14 q32 |
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deiodinase, iodothyronine, type III opposite strand
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| Identifiers | |
| Symbol | DIO3OS C14orf134 |
| HUGO | 20348 |
| Entrez | 64150 |
| OMIM | 608523 |
| RefSeq | NM_022345 |
| UniProt | Q9HAR6 |
| Other data | |
| Locus | Chr. 14 q32.33 |
Deiodinase (EC 1.97.1.10) is an enzyme important in the action of thyroid hormones.
Deiodinases are unusual in that the enzyme contains selenium, in the form of an otherwise rare amino acid selenocysteine.
Contents |
In the tissues, deiodinases can either activate or inactivate thyroid hormones:
- Activation occurs by conversion of the prohormone thyroxine (T4) to the active hormone triiodothyronine (T3) through the removal of an iodine atom on the outer ring.
- Inactivation of thyroid hormones occurs by removal of an iodine atom on the inner ring which converts thyroxine to the inactive reverse triiodothyronine (rT3), or which converts the active triiodothyronine to the inactive diiodothyronine (T2). The major part of thyroxine deiodination occurs within the target cells.
In most vertebrates, there are three types of enzymes that can deiodinate thyroid hormones:
| Type | Location | Function |
| type I (DI) | is commonly found in the liver, kidney, muscle tissue and thyroid gland | DI can deiodinate both rings |
| type II deiodinase (DII) | mostly in the brain but also in the testis and thyroid | DII can only deiodinate the outer ring of the prohormone thyroxine (or the metabolically inactive reverse triiodothyronine) and is the major activating enzyme |
| type III deiodinase (DIII) | found in the fetal tissue and the placenta | DIII can only deiodinate the inner ring of thyroxine or triiodothyronine and is the major inactivating enzyme |
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