Adrm1 is an integral Ub receptor of the 26S proteasome. Adrm1 binds both Ub and polyUb chains via its N-terminal Pru domain. The Pru domain also binds S1 to locate Adrm1 on the 26S proteasome. The C-terminal domain of Adrm1 binds the deubiquitinating enz