ADRM1 (Rpn13) interacts with the 26S proteasome base unit PRDM1 (Rpn2) via its amino-terminus and is found in the majority of 26S proteasomes. ADRM1 can bind K48-linked di-Ubiquitin (Schreiner et al. 2008, Husnjak et al. 2008) and several de-ubiquitinating enzymes (DUBs) including PSDM14 (Rpn11, POH1), part of the 26S proteasome, and USP14 (Borodovsky et al. 2001, Reyes-Turcu et al. 2009). These proteasome-associated DUBs disassemble poly-Ub chains and recycle ubiquitin during proteasomal degradation. They may also act to prevent the degradation of mis-tagged proteins.