# MUS81

Source: https://onco.cc/targets/mus81/  
OnCo record `mus81` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

MUS81 (Structure-specific endonuclease subunit MUS81) is an enzyme. The public catalogues list it as a drug target, a biomarker and a DNA repair gene, and clinical evidence ties its variants to diagnosis, prognosis or drug response. Tied to Ovarian cancer.

## Summary

Catalytic subunit of two functionally distinct, structure-specific, heterodimeric DNA endonucleases MUS81-EME1 and MUS81-EME2 that are involved in the maintenance of genome stability. Both endonucleases have essentially the same substrate specificity though MUS81-EME2 is more active than its MUS81-EME1 counterpart. Both cleave 3'-flaps and nicked Holliday junctions, and exhibit limited endonuclease activity with 5' flaps and nicked double-stranded DNAs.

CIViC holds 1 clinical evidence item and 0 assertions across 2 variants, naming Olaparib.

## Fields

- Kind: Target
- Last checked: 2026-09-23
- Also known as: MUS81 structure-specific endonuclease subunit; Structure-specific endonuclease subunit MUS81; FLJ44872; SLX3
- Tags: cancer-genes-wave
- Symbol: MUS81
- Class: enzyme
- Biology: Catalytic subunit of two functionally distinct, structure-specific, heterodimeric DNA endonucleases MUS81-EME1 and MUS81-EME2 that are involved in the maintenance of genome stability. Both endonucleases have essentially the same substrate specificity though MUS81-EME2 is more active than its MUS81-EME1 counterpart. Both cleave 3'-flaps and nicked Holliday junctions, and exhibit limited endonuclease activity with 5' flaps and nicked double-stranded DNAs. MUS81-EME2 which is active during the replication of DNA is more specifically involved in replication fork processing. Replication forks frequently encounter obstacles to their passage, including DNA base lesions, DNA interstrand cross-links, difficult-to-replicate sequences, transcription bubbles, or tightly bound proteins. One mechanism for the restart of a stalled replication fork involves nucleolytic cleavage mediated by the MUS81-EME2 endonuclease. Location: Nucleus, nucleolus (UniProt). Locus 11q13 (HGNC).
- Where found: Ovarian cancer: CIViC evidence names this disease

## 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: CIViC lists 1 therapies; CIViC holds 1 clinical evidence items on its variants; UniProt keyword "DNA repair". Evidence tier "clinical-evidence" is the strongest of those signals.
- Prevalence not recorded: none of the sources gives a positivity rate.

## Sources

- HGNC HGNC:29814: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:29814
- UniProt Q96NY9: https://www.uniprot.org/uniprotkb/Q96NY9/entry
- NCBI Gene 80198: https://www.ncbi.nlm.nih.gov/gene/80198
- Ensembl ENSG00000172732: https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000172732

## Connected records

- collections: [CIViC](https://onco.cc/collections/civic/)
- cancers: [Ovarian cancer](https://onco.cc/cancers/ovarian/)

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JSON: https://onco.cc/api/v1/entities/mus81.json