?Required for DNA repair.Binds to DDB2 to form the UV-damaged DNA-binding protein complex (the UV-DDB complex).The UV-DDB complex may recognize UV-induced DNA damage and recruit proteins of the nucleotide excision repair pathway (the NER pathway) to initiate DNA repair.The UV-DDB complex preferentially binds to cyclobutane pyrimidine dimers (CPD),6-4 photoproducts (6-4 PP),apurinic sites and short mismatches.Also appears to function as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes which mediate the ubiquitination and subsequent proteasomal degradation of target proteins.The functional specificity of the DCX E3 ubiquitin-protein ligase complex is determined by the variable substrate recognition component recruited by DDB1.DCX(DDB2) (also known as DDB1-CUL4-ROC1,CUL4-DDB-ROC1 and CUL4-DDB-RBX1) may ubiquitinate histone H2A,histone H3 and histone H4 at sites of UV-induced DNA damage.The ubiquitination of histones may facilitate their removal from the nucleosome and promote subsequent DNA repair.DCX(DDB2) also ubiquitinates XPC,which may enhance DNA-binding by XPC and promote NER.DCX(DTL) plays a role in PCNA-dependent polyubiquitination of CDT1 and MDM2-dependent ubiquitination of TP53 in response to radiation-induced DNA damage and during DNA replication.DCX(ERCC8) (the CSA complex) plays a role in transcription-coupled repair (TCR).May also play a role in ubiquitination of CDKN1B/p27kip when associated with CUL4 and SKP2.