May function as a substrate receptor for CUL4-DDB1 E3 ubiquitin-protein ligase complex. Protein modification; protein ubiquitination. Interacts with DDB1 and CUL4A. An intronic G-to-A transition (rs2535913) has been associated with leukocyte telomere length. The minor A allele is associated with shorter telomeres and lower expression in lymphoblastoid cells and in sun-exposed skin (PubMed:25624462).