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 (By similarity). Promotes proteasome dissociation under oxidative stress (PubMed:26802743). 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. Widely expressed (at protein level). Deficient mice are viable, fertile, and do not show any histological abnormalities. Under stressed condition, 26S proteasome dissociates in wild-type cells, but not in cells from deficient mice. Belongs to the ECM29 family. Intron retention.