SRD5A1: Steroid 5 Alpha-Reductase 1
Key enzyme in androgen metabolism and steroid hormone conversion
Gene Information Card
| Symbol | SRD5A1 |
|---|---|
| Full Name | Steroid 5 Alpha-Reductase 1 |
| Gene Type | Protein coding |
| Chromosomal Location | 5p15.31 |
| NCBI Gene ID | 6715 ncbi.nlm.nih.gov/gene/6715 |
| Ensembl ID | ENSG00000145545 |
| UniProt ID | P18405 |
| OMIM ID | 184753 |
| HGNC ID | 11284 |
| Aliases | 3-oxo-5α-steroid 4-dehydrogenase 1, S5AR1, SRD5A1L |
Description
SRD5A1 encodes steroid 5 alpha-reductase 1, an enzyme that catalyzes the conversion of testosterone into the more potent androgen dihydrotestosterone (DHT). This enzyme is expressed in various tissues including skin, liver, and prostate, and plays a critical role in androgen signaling, sexual differentiation, and hair growth. Mutations and altered expression of SRD5A1 are associated with disorders of sexual development, benign prostatic hyperplasia, and prostate cancer.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Benign prostatic hyperplasia | Increased SRD5A1 activity elevates DHT levels, promoting prostate cell proliferation | ClinVar, OMIM |
| Prostate cancer | Overexpression of SRD5A1 contributes to androgen-dependent tumor growth | COSMIC, NCBI |
| Androgenetic alopecia | Enhanced conversion of testosterone to DHT in scalp follicles leads to hair miniaturization | OMIM |
| 5-alpha-reductase deficiency (partial) | Loss-of-function mutations reduce DHT synthesis, impairing male sexual development | OMIM, ClinVar |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Prostate | 12.3 | Medium |
| Liver | 8.7 | Medium |
| Skin | 6.5 | Low |
| Adrenal gland | 4.2 | Low |
| Testis | 3.1 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| LNCaP (prostate cancer) | 15.2 | High expression |
| HepG2 (liver) | 9.8 | Moderate expression |
| HaCaT (keratinocyte) | 5.4 | Low expression |
| MCF-7 (breast cancer) | 2.1 | Very low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.680G>A (p.Arg227Gln) | Missense | <0.1% | Reduced enzyme activity; associated with partial 5-alpha-reductase deficiency |
| c.737G>A (p.Arg246Gln) | Missense | <0.1% | Loss of function; impaired DHT synthesis |
| c.1A>G (p.Met1Val) | Start loss | <0.1% | Complete loss of protein expression |
Mutation functional classification
Loss of Function (LOF)
Missense mutations (e.g., p.Arg227Gln, p.Arg246Gln) reduce or abolish enzymatic activity, leading to decreased DHT levels and impaired androgen signaling.
Gain of Function (GOF)
No confirmed gain-of-function mutations reported in SRD5A1.
Dominant Negative (DN)
No evidence of dominant-negative effects for SRD5A1 mutations.
View complete mutation data：
Gene Ontology (GO)
| • GO:0003854 - 3-oxo-5α-steroid 4-dehydrogenase activity | • GO:0006702 - androgen biosynthetic process |
| • GO:0005783 - endoplasmic reticulum membrane | • GO:0016021 - integral component of membrane |
| • GO:0042446 - hormone biosynthetic process |
Pathways
• Androgen biosynthesis (Reactome: R-HSA-196054)
• Metabolism of steroids (Reactome: R-HSA-8957322)
• Prostate cancer (KEGG: hsa05215)
Protein Summary
SRD5A1 is a 259-amino acid microsomal protein with a molecular weight of approximately 29.5 kDa. It contains a NADPH-binding domain and a steroid-binding domain, and functions as a homodimer. The enzyme reduces the double bond at the 4-5 position of steroid substrates, converting testosterone to DHT. It is inhibited by finasteride and dutasteride, which are used clinically for benign prostatic hyperplasia and androgenetic alopecia.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SRD5A1 Knockout HEK293 Cell Line | EDJ-KQ2660 | Human | 6715 | Details Get a Quote |
| SRD5A1 Knockout A-549 Cell Line | EDJ-KQ23441 | Human | 6715 | Details Get a Quote |
| SRD5A1 Knockout HCT 116 Cell Line | EDJ-KQ23442 | Human | 6715 | Details Get a Quote |
| SRD5A1 Knockout HeLa Cell Line | EDJ-KQ23443 | Human | 6715 | Details Get a Quote |
| SRD5A1 Knockout HAP1 Cell Line | EDC07946 | Human | 6715 | Details Get a Quote |
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