Adapter/scaffolding protein that binds to the 26S proteasome, motor proteins and other compartment specific proteins. May couple the proteasome to different compartments including endosome, endoplasmic reticulum and centrosome. May play a role in ERAD and other enhanced proteolysis. Promotes proteasome dissociation under oxidative stress. Non-stoichiometric component of the proteasome; associates with the 26S proteasome. Interacts (via N-terminus) with VPS11, VPS26A, VPS36, RAB11FIP4 and RABEP1. Interacts (via C-terminus) with DCTN1, DCTN2, KIF5B, MYH7, MYH10, MYO10 and ARF6. Belongs to the ECM29 family.