{"entity":{"id":"srd5a1","kind":"target","name":"SRD5A1","aka":["steroid 5 alpha-reductase 1","3-oxo-5-alpha-steroid 4-dehydrogenase 1"],"tldr":"SRD5A1 (3-oxo-5-alpha-steroid 4-dehydrogenase 1) 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":"Catalyses the irreversible stereospecific reduction of the delta 4,5 bond (double bond between carbons 4 and 5) of various 3-oxo steroids (3-keto steroids) producing their 5alpha dihydro-3-oxo forms. Converts testosterone into 5-alpha-dihydrotestosterone (DHT), a more potent androgen as it is the preferred ligand for androgen receptor (AR) transactivation, making this reaction a key step in male sexual differentiation during development. Besides testosterone, it can also act on other steroids, including progesterone, androstenedione, and corticoids, producing metabolites with diverse roles.\n\nOpen Targets scores its association with cancer at 0.61 (direct and indirect evidence; datatypes literature 0.82, genetic association 0.03, clinical 0.96).","asOf":"2026-09-23","links":[{"label":"HGNC HGNC:11284","url":"https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:11284"},{"label":"UniProt P18405","url":"https://www.uniprot.org/uniprotkb/P18405/entry"},{"label":"NCBI Gene 6715","url":"https://www.ncbi.nlm.nih.gov/gene/6715"},{"label":"Ensembl ENSG00000145545","url":"https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000145545"}],"tags":["cancer-genes-wave"],"related":["open-targets"],"cancers":["prostate"],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"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."],"provenance":{"editedBy":"scripts/fetch-cancer-genes.ts (CIViC, Open Targets, IntOGen, HGNC, UniProt)","editedOn":"2026-09-23"},"symbol":"SRD5A1","role":["drug-target"],"evidenceTier":"approved-drug","sources":[{"label":"HGNC HGNC:11284","url":"https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:11284","note":"approved symbol, name, aliases, locus and cross-references (hgnc_complete_set.txt)"},{"label":"UniProt P18405","url":"https://www.uniprot.org/uniprotkb/P18405/entry","note":"protein name, function text, keywords and locations (REST API)"},{"label":"Open Targets ENSG00000145545","url":"https://platform.opentargets.org/target/ENSG00000145545/associations","note":"association with cancer (MONDO_0004992) 0.61; per-cancer scores at or above 0.5: prostate cancer 0.60 (GraphQL API, CC0)"}],"distribution":"one-type","specificityNote":"Specificity not established: no corpus medicine is aimed at it and the catalogues give it only the role drug-target; HPA finds the RNA tissue enhanced, which says where the protein sits but not whether the tumour differs from normal tissue. HPA SRD5A1: RNA tissue enhanced (liver 27 nTPM); high antibody staining in 7 normal tissues; highest cancer staining prostate cancer (4 of 12 high). Distribution: 1 cancer family in the corpus carries a prevalence row, label threshold or catalogue link for it (Prostate cancer); Open Targets associates it with 3 specific cancer types at or above 0.5 (benign prostatic hyperplasia, prostate cancer, prostate carcinoma); the corpus evidence decides and the Open Targets list is quoted for comparison. (No rule of scripts/fetch-target-specificity.ts fired.)","specificitySources":[{"label":"Human Protein Atlas SRD5A1 tissue","url":"https://www.proteinatlas.org/ENSG00000145545-SRD5A1/tissue","note":"RNA tissue and blood lineage specificity, normal tissue antibody staining (version 25.1, CC BY-SA 3.0)"},{"label":"Open Targets ENSG00000145545 associations","url":"https://platform.opentargets.org/target/ENSG00000145545/associations","note":"cancer associations at or above 0.5 (CC0)"}],"hgnc":"HGNC:11284","ensembl":"ENSG00000145545","uniprot":"P18405","entrez":"6715","firstDescribed":1990,"firstDescribedBasis":"sequence","firstDescribedNote":"Earliest sequence paper UniProt cites for the protein: Andersson et al, Proc. Natl. Acad. Sci. U.S.A, 1990, \"Structural and biochemical properties of cloned and expressed human and rat steroid 5 alpha-reductases\".","firstDescribedSource":"https://pubmed.ncbi.nlm.nih.gov/2339109/","biology":"Catalyses the irreversible stereospecific reduction of the delta 4,5 bond (double bond between carbons 4 and 5) of various 3-oxo steroids (3-keto steroids) producing their 5alpha dihydro-3-oxo forms. Converts testosterone into 5-alpha-dihydrotestosterone (DHT), a more potent androgen as it is the preferred ligand for androgen receptor (AR) transactivation, making this reaction a key step in male sexual differentiation during development. Besides testosterone, it can also act on other steroids, including progesterone, androstenedione, and corticoids, producing metabolites with diverse roles. Hence, it plays a central role in sexual differentiation and androgen physiology. Location: Microsome membrane; Endoplasmic reticulum membrane (UniProt). Locus 5p15.31 (HGNC).","whereFound":["Prostate cancer: Open Targets association 0.60 with prostate cancer (MONDO_0008315)"],"targetClass":"enzyme","prevalence":[]},"route":"/targets/srd5a1/","neighbours":{"collection":[{"id":"open-targets","kind":"collection","name":"Open Targets Platform","route":"/collections/open-targets/"}],"cancer":[{"id":"prostate","kind":"cancer","name":"Prostate cancer","route":"/cancers/prostate/"}]}}