# SRD5A3

Source: https://onco.cc/targets/srd5a3/  
OnCo record `srd5a3` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

SRD5A3 (Polyprenal reductase) is an enzyme. The public catalogues list it as a drug target, and an approved or late-stage drug is recorded against it. Tied to Prostate cancer.

## Summary

Plays a key role in early steps of protein N-linked glycosylation by being involved in the conversion of polyprenol into dolichol. Acts as a polyprenal reductase that mediates the reduction of polyprenal into dolichal in a NADP-dependent mechanism. Dolichols are required for the synthesis of dolichol-linked monosaccharides and the oligosaccharide precursor used for N-glycosylation.

Open Targets scores its association with cancer at 0.61 (direct and indirect evidence; datatypes literature 0.93, genetic association 0.00, clinical 0.96).

## Fields

- Kind: Target
- Last checked: 2026-09-23
- Also known as: steroid 5 alpha-reductase 3; Polyprenal reductase; FLJ13352; SRD5A2L; SRD5A2L1
- Tags: cancer-genes-wave
- Symbol: SRD5A3
- Class: enzyme
- Biology: Plays a key role in early steps of protein N-linked glycosylation by being involved in the conversion of polyprenol into dolichol. Acts as a polyprenal reductase that mediates the reduction of polyprenal into dolichal in a NADP-dependent mechanism. Dolichols are required for the synthesis of dolichol-linked monosaccharides and the oligosaccharide precursor used for N-glycosylation. Also able to convert testosterone (T) into 5-alpha-dihydrotestosterone (DHT). Location: Endoplasmic reticulum membrane (UniProt). Locus 4q12 (HGNC).
- Where found: Prostate cancer: Open Targets association 0.59 with prostate cancer (MONDO_0008315)

## Notes

- Written by scripts/fetch-cancer-genes.ts from CIViC, Open Targets, IntOGen, HGNC and UniProt; the function text is UniProt's, condensed and in UK spelling. Roles: Open Targets known-drug datatype score 0.96. Evidence tier "approved-drug" is the strongest of those signals.
- Prevalence not recorded: none of the sources gives a positivity rate.

## Sources

- HGNC HGNC:25812: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:25812
- UniProt Q9H8P0: https://www.uniprot.org/uniprotkb/Q9H8P0/entry
- NCBI Gene 79644: https://www.ncbi.nlm.nih.gov/gene/79644
- Ensembl ENSG00000128039: https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000128039

## Connected records

- collections: [Open Targets Platform](https://onco.cc/collections/open-targets/)
- cancers: [Prostate cancer](https://onco.cc/cancers/prostate/)

---
JSON: https://onco.cc/api/v1/entities/srd5a3.json