SRD5A3
Steroid 5 Alpha-Reductase 3
Gene Information Card
| Symbol | SRD5A3 |
|---|---|
| Full Name | Steroid 5 Alpha-Reductase 3 |
| Gene Type | Protein coding |
| Chromosomal Location | 4q12 |
| NCBI Gene ID | 79644 ncbi.nlm.nih.gov/gene/79644 |
| Ensembl ID | ENSG00000138674 |
| UniProt ID | Q9H8P0 |
| OMIM ID | 611715 |
| HGNC ID | 25812 |
| Aliases | CDG1Q, SRD5A2L, SRD5A2L1, MGC119984 |
Description
SRD5A3 (Steroid 5 Alpha-Reductase 3) is a protein-coding gene that encodes an enzyme involved in the reduction of polyprenol to dolichol, a critical step in the dolichol-phosphate pathway required for N-linked protein glycosylation. Mutations in this gene cause congenital disorder of glycosylation type 1Q (CDG1Q), characterized by intellectual disability, cerebellar atrophy, and ophthalmologic abnormalities.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Congenital disorder of glycosylation type 1Q (CDG1Q) | Loss-of-function mutations impair dolichol synthesis, disrupting N-glycosylation | OMIM #612379; multiple case reports (PMID: 20802464, 22966046) |
| Kahrizi syndrome | Biallelic SRD5A3 mutations lead to intellectual disability, cataracts, and coloboma | OMIM #612713; PMID: 20802464 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 10.2 | Medium |
| Adrenal gland | 8.5 | Medium |
| Liver | 6.1 | Low |
| Brain (cerebellum) | 5.3 | Low |
| Kidney | 4.8 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK293 | 12.3 | Embryonic kidney; moderate expression |
| HepG2 | 7.8 | Hepatocellular carcinoma; low expression |
| SH-SY5Y | 6.5 | Neuroblastoma; low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.57G>A (p.Trp19*) | Nonsense | Rare | Loss of function; truncation |
| c.200C>T (p.Pro67Leu) | Missense | Rare | Loss of function; impaired enzyme activity |
| c.364C>T (p.Arg122*) | Nonsense | Rare | Loss of function; premature stop |
| c.458G>A (p.Arg153Gln) | Missense | Rare | Loss of function; reduced dolichol synthesis |
Mutation functional classification
Loss of Function (LOF)
Most reported SRD5A3 mutations are loss-of-function, leading to reduced or absent enzyme activity and impaired dolichol-dependent glycosylation.
Gain of Function (GOF)
No gain-of-function mutations have been described for SRD5A3.
Dominant Negative (DN)
No dominant-negative mutations have been reported; inheritance is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
| • 3-oxo-5-alpha-steroid 4-dehydrogenase activity (GO:0003854) | • NADP binding (GO:0050661) |
| • dolichol biosynthetic process (GO:0016093) | • protein N-linked glycosylation (GO:0006487) |
| • endoplasmic reticulum membrane (GO:0005789) |
Pathways
• Dolichol phosphate biosynthesis (Reactome: R-HSA-446193)
• N-glycan biosynthesis (KEGG: hsa00510)
• Metabolism of steroids (KEGG: hsa00140)
Protein Summary
SRD5A3 encodes a 318-amino acid transmembrane protein localized to the endoplasmic reticulum. It catalyzes the NADPH-dependent reduction of polyprenol to dolichol, a lipid carrier essential for the assembly of N-glycans. The enzyme belongs to the steroid 5-alpha-reductase family but primarily functions in glycosylation rather than steroid metabolism. Deficiency leads to accumulation of polyprenol and defective N-glycosylation, causing multisystem disease.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SRD5A3 Knockout HEK293 Cell Line | EDJ-KQ16792 | Human | 79644 | Details Get a Quote |
| SRD5A3 Knockout HeLa Cell Line | EDJ-KQ47220 | Human | 79644 | Details Get a Quote |
| SRD5A3 Knockout A-549 Cell Line | EDJ-KQ48509 | Human | 79644 | Details Get a Quote |
| SRD5A3 Knockout HCT 116 Cell Line | EDJ-KQ48510 | Human | 79644 | Details Get a Quote |
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