Substrate-recognition component of the CSA complex, a DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complex, involved in transcription-coupled nucleotide excision repair (By similarity). The CSA complex (DCX(ERCC8) complex) promotes the ubiquitination and subsequent proteasomal degradation of ERCC6 in a UV-dependent manner; ERCC6 degradation is essential for the recovery of RNA synthesis after transcription-coupled repair (By similarity). It is required for the recruitment of XAB2, HMGN1 and TCEA1/TFIIS to a transcription-coupled repair complex which removes RNA polymerase II-blocking lesions from the transcribed strand of active genes (By similarity). Plays a role in DNA single-strand and double-strand breaks (DSSBs) repair; involved in repair of DSSBs by non-homologous end joining (NHEJ) (By similarity). Protein modification; protein ubiquitination. Part of the CSA complex (DCX(ERCC8) complex), a DCX E3 ubiquitin-protein ligase complex containing ERCC8, RBX1, DDB1 and CUL4A; the CSA complex interacts with RNA polymerase II; upon UV irradiation it interacts with the COP9 signalosome and preferentially with the hyperphosphorylated form of RNA polymerase II. Interacts with ERCC6 and KIAA1530/UVSSA. Interacts with a subunit of RNA polymerase II TFIIH. Interacts with DDB1. UV-induced translocation to the nuclear matrix is dependent on ERCC6. Ercc8 deficient mice develop normally, but show a loss of retinal photoreceptors after 4 months of age, and enhanced UV-sensitivity.