A method for screening a compound to determine whether the compound is a proteasome deubiquitinating inhibitor of high specificity comprises contacting the compound with human 19S regulatory particles (19S RP) of 26S proteasome and determining whether the compound inhibits activity of deubiquitinating (DUB) enzymes UCHL5 and USP14; inhibition of UCHL5 and USCP14 activities indicates that the compound is a proteasome deubiquitinating inhibitor of high specificity.
Protease deubiquitinating inhibitor screening