This gene encodes a structure-specific endonuclease subunit. The encoded protein contains a central BTB domain and it forms a multiprotein complex with the ERCC4(XPF)-ERCC1, MUS81-EME1, and SLX1 endonucleases, and also associates with MSH2/MSH3 mismatch repair complex, telomere binding complex TERF2(TRF2)-TERF2IP(RAP1), the protein kinase PLK1 and the uncharacterized protein C20orf94. The multiprotein complex is required for repair of specific types of DNA lesions and is critical for cellular responses to replication fork failure. The encoded protein acts as a docking platform for the assembly of multiple structure-specific endonucleases.