May function as a substrate receptor for CUL4-DDB1 E3 ubiquitin-protein ligase complex. Protein modification; protein ubiquitination. Interacts with DDB1, CUL4A and CUL4B. According to PubMed:19026396, it is a nucleolar protein, while sequence analysis programs clearly predict 2 transmembrane regions. Ubiquitously expressed in the embryo, with higher expression in brain, liver and skin tissues.