The DDB1–DDB2–CUL4–RBX1 complex serves as the primary detection device for UV‐induced lesions in the genome. It simultaneously functions as a CUL4 type E3 ubiquitin ligase. We review the current understanding of this dual function ubiquitin ligase and damage detection complex. The DDB2 damage binding module is merely one of a large family of possible DDB1–CUL4 associated factors (DCAF), most of which are substrate receptors for other DDB1–CUL4 complexes. DDB2 and the Cockayne‐syndrome A protein (CSA) function in nucleotide excision repair, whereas the remaining receptors operate in a wide range of other biological pathways. We will examine the modular architecture of DDB1–CUL4 in complex with DDB2, CSA and CDT2 focusing on shared architectural, targeting and regulatory principles.