TFIIH does not use XPG to locate damaged DNA. TFIIH contains XPD (ERCC2) and XPB (ERCC3) helicases, which unwind DNA near transcription start sites. XPG (ERCC5) is part of the nucleotide excision repair machinery, where it functions in DNA unwinding in collaboration with ERCC1 as well as enzymatic cleavage of damaged DNA after verification by other proteins in the damage-sensing multi-protein complex.