Rpn13 is a known component of the proteasome. Especially, Rpn13 binds ubiquitin-like domains of the UBL/UBA family of ubiquitin receptors. Rpn13, as an ubiquitin receptor, offers a docking position for ubiquitinated substrate. RA375 is a RPN13 inhibitor. Treatment with RA375 causes a rapid and profound accumulation of high molecular weight polyubiquitinated proteins. RA375...