May negatively regulate the ATPase activity of VCP, an ATP-driven segregase that associates with different cofactors to control a wide variety of cellular processes. As a cofactor of VCP, it may play a role in the transport of CAV1 to lysosomes for degradation. It may also play a role in endoplasmic reticulum-associated degradation (ERAD) of misfolded proteins. Together with VCP and other cofactors, it may play a role in macroautophagy, regulating for instance the clearance of damaged lysosomes. Interacts with VCP through the PUB domain (via C-terminus) and VIM motif (via N-terminus); the interaction is direct. Forms a ternary complex with CAV1 and VCP. Interacts with SYVN1. Interacts with HERPUD1. Interacts with VCPKMT. May interact with DERL1. Interacts with PLAA, VCP and YOD1; may form a complex involved in macroautophagy. Interacts with LMAN1. Localizes at the centrosome both in interphase and during mitosis. May be recruited to endosomal and lysosomal membranes as part of a ternary complex with CAV1 and VCP. Recruited to damaged lysosomes decorated with K48-linked ubiquitin chains. Widely expressed (at protein level). Highest expression in brain (at protein level). The UBX domain lacks key residues critical for VCP binding.