ADRM1 (also called Rpn13) interacts with the 26S proteasome base unit PRDM1 (Rpn2) via its amino-terminus and is found in the majority of 26S proteasomes. It is a receptor for Ubiquitin (Ub) that can bind K48-linked di-Ub (Schreiner et al. 2008, Husnjak et al. 2008) and de-ubiquitinating enzymes (DUBs) such as PSMD14 (Rpn11, POH1), USP14, and UCHL5 (UCH37) (Reyes-Turcu et al., 2009). Together, these DUBs disassemble poly-Ub chains and recycle ubiquitin during proteasomal degradation.