Deiodinase
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| deiodinase, iodothyronine, type I
| |
| Identifiers | |
| Symbol | DIO1 |
| Alt. Symbols | TXDI1 |
| Entrez | 1733 |
| HUGO | 2883 |
| OMIM | 147892 |
| RefSeq | NM_000792 |
| UniProt | P49895 |
| Other data | |
| EC number | 1.97.1.10 |
| Locus | Chr. 1 p32-p33 |
| deiodinase, iodothyronine, type II
| |
| Identifiers | |
| Symbol | DIO2 |
| Entrez | 1734 |
| HUGO | 2884 |
| OMIM | 601413 |
| RefSeq | NM_000793 |
| UniProt | Q92813 |
| Other data | |
| Locus | Chr. 14 q24.2-24.3 |
| deiodinase, iodothyronine, type III
| |
| Identifiers | |
| Symbol | DIO3 |
| Alt. Symbols | TXDI3 |
| Entrez | 1735 |
| HUGO | 2885 |
| OMIM | 601038 |
| RefSeq | NM_001362 |
| UniProt | P55073 |
| Other data | |
| Locus | Chr. 14 q32 |
| deiodinase, iodothyronine, type III opposite strand
| |
| Identifiers | |
| Symbol | DIO3OS |
| Alt. Symbols | C14orf134 |
| Entrez | 64150 |
| HUGO | 20348 |
| 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.
Activation and inactivation
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.
Types
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 |
Reactions
External links
nl:Deiodinase
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
