DDB1 represents "DNA damage-binding protein 1", a subunit of DCX (DDB1-CUL4-X-box) E3 ligase complex. Members of DDB1 family can recruit substrate-specific recognizing and binding adaptors to the DCX complex. The substrate-specific adaptors contain two main classes, DCAF (DDB1- and CUL4-associated factor) and WDR (WD40-repeat) proteins (1,2). As conserved in eukaryote, the DDB1-containting DCX complex is a Cullin-RING ubiquitin ligase that can regulate DNA replication and transcription, DNA repair, and can also be hijacked by pathogenic viruses to make for viral infection (3).

1. Lee, J. and Zhou, P. (2007). DCAFs, the missing link of the CUL4-DDB1 ubiquitin ligase. Mol. Cell, 26, 775-780. PMID: 17588513

2. Higa, L.A., Wu, M., Ye, T., Kobayashi, R., Sun, H. and Zhang, H. (2006). CUL4-DDB1 ubiquitin ligase interacts with multiple WD40-repeat proteins and regulates histone methylation. Nat Cell. Biol., 8, 1277-1283.PMID: 17041588

3. Angers, S., Li, T., Yi, X., MacCoss, M.J., Moon, R.T. and Zheng, N. (2006). Molecular architecture and assembly of the DDB1-CUL4A ubiquitin ligase machinery. Nature, 443, 590-593. PMID: 16964240