Catalytic component of a structure-specific DNA repair endonuclease responsible for the 5-prime incision during DNA repair, and which is essential for nucleotide excision repair (NER) and interstrand cross-link (ICL) repair. Heterodimer composed of ERCC1 and ERCC4/XPF. Interacts with SLX4/BTBD12; this interaction is direct and links the ERCC1-ERCC4/XPF complex to SLX4, which may coordinate the action of the structure-specific endonuclease during DNA repair. Localizes to sites of DNA damage. Acetylation at Lys-912 by KAT5 promotes interaction with ERCC1 by disrupting a salt bridge between Asp-908 and Lys-912, thereby exposing a second binding site for ERCC1 (By similarity). Deacetylated by SIRT1 (By similarity). Belongs to the XPF family.