DDB1 was originally identified as a large subunit of damaged DNA-binding protein (DDB), which plays a role in DNA repair. DDB1 also functions as an adaptor molecule of Cul4/DDB1 ubiquitin E3 ligase and participates in various cellular processes.

References:
1) Wakasugi M, Matsuura K, Nagasawa A, Fu D, Shimizu H, Yamamoto K, Takeda S, Matsunaga T. (2007) DDB1 gene disruption causes a severe growth defect and apoptosis in chicken DT40 cells. Biochem Biophys Res Commun. 364(4):771-7. PMID: 17976535.