3β-Hydroxysteroid dehydrogenase
3β-Hydroxysteroid dehydrogenase/Δ5-4 isomerase (3β-HSD) (EC 1.1.1.145) is an enzyme that catalyzes the biosynthesis of the steroid progesterone from pregnenolone, 17α-hydroxyprogesterone from 17α-hydroxypregnenolone, and androstenedione from dehydroepiandrosterone (DHEA) in the adrenal gland. It is the only enzyme in the adrenal pathway of corticosteroid synthesis that is not a member of the cytochrome P450 family. It is also present in other steroid-producing tissues, including the ovary, testis and placenta. In humans, there are two 3β-HSD isozymes encoded by the HSD3B1 and HSD3B2 genes.
| 3β-hydroxysteroid dehydrogenase/Δ-5-4 isomerase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC no. | 1.1.1.145 | ||||||||
| CAS no. | 9044-85-3 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
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| 3β-Hydroxysteroid dehydrogenase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| Symbol | HSD3B | ||||||||
| Pfam | PF01073 | ||||||||
| InterPro | IPR002225 | ||||||||
| Membranome | 245 | ||||||||
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| hydroxy-Δ-5-steroid dehydrogenase, 3β- and steroid Δ-isomerase 1 | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Symbol | HSD3B1 | ||||||
| Alt. symbols | HSDB3, HSD3B | ||||||
| NCBI gene | 3283 | ||||||
| HGNC | 5217 | ||||||
| OMIM | 109715 | ||||||
| RefSeq | NM_000862 | ||||||
| UniProt | P14060 | ||||||
| Other data | |||||||
| EC number | 1.1.1.145 | ||||||
| Locus | Chr. 1 p13-p11 | ||||||
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| hydroxy-Δ-5-steroid dehydrogenase, 3β- and steroid Δ-isomerase 2 | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Symbol | HSD3B2 | ||||||
| NCBI gene | 3284 | ||||||
| HGNC | 5218 | ||||||
| OMIM | 613890 | ||||||
| RefSeq | NM_000198 | ||||||
| UniProt | P26439 | ||||||
| Other data | |||||||
| EC number | 1.1.1.145 | ||||||
| Locus | Chr. 1 p13.1 | ||||||
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3β-HSD is also known as delta Δ5-4-isomerase, which catalyzes the oxidative conversion of Δ5-3β-hydroxysteroids to the Δ4-3-keto configuration and is, therefore, essential for the biosynthesis of all classes of hormonal steroids, namely progesterone, glucocorticoids, mineralocorticoids, androgens, and estrogens.
The 3β-HSD complex is responsible for the conversion of:
- Pregnenolone to progesterone
- 17α-Hydroxypregnenolone to 17α-hydroxyprogesterone
- DHEA to androstenedione
- Androstenediol to testosterone
- Androstadienol to androstadienone