Recombinant Recombinant human complex of RBx1 (ring-box 1), CUL4B (cullin 4B), DBB1 (damage specific DNA binding protein 1), DCAF15 (DDB1 and CUL4 associated factor 15), and DDA1 (DET1 and DDB1 associated 1). RBx1, full length, encompassing amino acids 2-108(end). This construct contains an N-terminal His-tag (6xHis). CUL4B, encompassing amino acids 3-913(end). This construct contains an N-terminal His-tag (6xHis). DBB1, full length, encompassing amino acids 2-1140(end). This construct contains an N-terminal Flag-tag. DCAF15, full length, encompassing amino acids 2-600(end). This construct contains an N-terminal Flag-tag. DDA1, full length, encompassing amino acids 2-102(end). This construct contains an N-terminal Flag-tag. These recombinant proteins are co-expressed in a HEK293 expression system and affinity purified.