May function as a proteasomal ubiquitin receptor. May promote the deubiquitinating activity associated with the 26S proteasome. Component of the 19S proteasome regulatory particle complex (By similarity). The 26S proteasome consists of a 20S core particle (CP) and two 19S regulatory subunits (RP) (By similarity). Interacts with deubiquitinase ubh-4 (PubMed:23770237). The Pru (pleckstrin-like receptor for ubiquitin) domain mediates interactions with rpn-2 and ubiquitin. Preferential binding to the proximal subunit of K48-linked diubiquitin allows ubh-4 access to the distal subunit. Belongs to the ADRM1 family.