Probably acts as an adapter for ATPase cdc-48.1 and/or cdc-48.2, conferring substrate specificity. Unlike other UBX domain-containing protein does not bind 'Lys-48'-polyubiquitinated chain. Forms a complex composed of deubiquitinating enzyme atx-3, adapter ubxn-5 and cdc-48.1. Interacts with atx-3 (via C-terminus). Interacts with cdc-48.1 (via N-terminus) and cdc-48.2. Specifically expressed in the germline. Expressed at L4 larval stage and to a lesser extent in adults.