Ubiquitin-binding adapter that links a subset of NEDD8-associated cullin ring ligases (CRLs) to the segregase VCP/p97, to regulate turnover of their ubiquitination substrates (By similarity). Interacts with neddylated CUL2, ubiquitinated HIF1A, and VCP/p97. The UIM (ubiquitin-interacting motif) is required to engage the NEDD8 modification on cullins. The UBX domain mediates interaction with VCP/p97. The UBA domain is required for binding ubiquitinated-protein substrates.