Cullin 4B (CUL4B)

Cullin-4B is a member of the cullin family. The encoded protein forms a complex that functions as an E3 ubiquitin ligase and catalyzes the polyubiquitination of specific protein substrates in the cell. The protein interacts with a ring finger protein, and is required for the proteolysis of several regulators of DNA replication including chromatin licensing and DNA replication factor 1 and cyclin E. Multiple transcript variants encoding different isoforms have been found for this gene.

Complex assembly and ubiquitin ligase activity of CUL4B(AHR) in vitro and in vivo are dependent on the AHR ligand. In the CUL4B(AHR) complex, ligand-activated AHR acts as a substrate-specific adaptor component that targets sex steroid receptors for degradation.