OnCo

TOP3A (DNA topoisomerase 3-alpha) is an enzyme. In the public catalogues the evidence so far is association rather than a proven role. This dossier gathers the 0 products (0 approved), 0 trials, 0 pathways and 0 resistance routes in the corpus that involve it, with external identifiers so it can be joined to UniProt, ChEMBL, Open Targets and the rest of biology.

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).

Class: enzyme · Gene: TOP3A · Facts checked 2026-09-23 · Target page

External identifiers

Built from HGNC, Ensembl, UniProt and ChEMBL ids

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Companion diagnostics

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Literature

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Query for this target: (TITLE:"TOP3A" OR ABSTRACT:"TOP3A" OR TITLE:"DNA topoisomerase III alpha" OR ABSTRACT:"DNA topoisomerase III alpha" OR TITLE:"DNA topoisomerase 3-alpha" OR ABSTRACT:"DNA topoisomerase 3-alpha" OR TITLE:"ZGRF7" OR ABSTRACT:"ZGRF7" OR TITLE:"TOP3" OR ABSTRACT:"TOP3") AND (cancer OR tumor OR tumour OR oncology OR carcinoma OR lymphoma OR leukemia OR leukaemia OR myeloma OR sarcoma OR melanoma OR glioma). Results are unfiltered search hits about TOP3A, not a curated reading list.

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The dossier as machine-readable JSON: identifiers from HGNC, Ensembl, UniProt and ChEMBL, products with status, trials, pathways, hotspots, open questions and assays. The full entity record is in the open API at /api/v1/entities/top3a.json. Licence CC BY-NC 4.0.