{"entity":{"id":"top3a","kind":"target","name":"TOP3A","aka":["DNA topoisomerase III alpha","DNA topoisomerase 3-alpha","ZGRF7","TOP3"],"tldr":"TOP3A (DNA topoisomerase 3-alpha) is an enzyme. In the public catalogues the evidence so far is association rather than a proven role.","summary":"Releases the supercoiling and torsional tension of DNA introduced during the DNA replication and transcription by transiently cleaving and rejoining one strand of the DNA duplex. Introduces a single-strand break via transesterification at a target site in duplex DNA. The scissile phosphodiester is attacked by the catalytic tyrosine of the enzyme, resulting in the formation of a DNA-(5'-phosphotyrosyl)-enzyme intermediate and the expulsion of a 3'-OH DNA strand.\n\nOpen Targets scores its association with cancer at 0.55 (direct and indirect evidence; datatypes literature 0.83, affected pathway 0.87, genetic association 0.00).","asOf":"2026-09-23","links":[{"label":"HGNC HGNC:11992","url":"https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:11992"},{"label":"UniProt Q13472","url":"https://www.uniprot.org/uniprotkb/Q13472/entry"},{"label":"NCBI Gene 7156","url":"https://www.ncbi.nlm.nih.gov/gene/7156"},{"label":"Ensembl ENSG00000177302","url":"https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000177302"}],"tags":["cancer-genes-wave"],"related":["open-targets"],"cancers":[],"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: none stated by the sources. Evidence tier \"association-only\" 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":"TOP3A","role":[],"evidenceTier":"association-only","sources":[{"label":"HGNC HGNC:11992","url":"https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:11992","note":"approved symbol, name, aliases, locus and cross-references (hgnc_complete_set.txt)"},{"label":"UniProt Q13472","url":"https://www.uniprot.org/uniprotkb/Q13472/entry","note":"protein name, function text, keywords and locations (REST API)"},{"label":"Open Targets ENSG00000177302","url":"https://platform.opentargets.org/target/ENSG00000177302/associations","note":"association with cancer (MONDO_0004992) 0.55;  (GraphQL API, CC0)"}],"hgnc":"HGNC:11992","ensembl":"ENSG00000177302","uniprot":"Q13472","entrez":"7156","biology":"Releases the supercoiling and torsional tension of DNA introduced during the DNA replication and transcription by transiently cleaving and rejoining one strand of the DNA duplex. Introduces a single-strand break via transesterification at a target site in duplex DNA. The scissile phosphodiester is attacked by the catalytic tyrosine of the enzyme, resulting in the formation of a DNA-(5'-phosphotyrosyl)-enzyme intermediate and the expulsion of a 3'-OH DNA strand. The free DNA strand then undergoes passage around the unbroken strand thus removing DNA supercoils. Finally, in the religation step, the DNA 3'-OH attacks the covalent intermediate to expel the active-site tyrosine and restore the DNA phosphodiester backbone. As an essential component of the RMI complex it is involved in chromosome separation and the processing of homologous recombination intermediates to limit DNA crossover formation in cells. Location: Mitochondrion matrix (UniProt). Locus 17p11.2 (HGNC).","whereFound":[],"targetClass":"enzyme","prevalence":[]},"route":"/targets/top3a/","neighbours":{"collection":[{"id":"open-targets","kind":"collection","name":"Open Targets Platform","route":"/collections/open-targets/"}]}}