Dephosphorylates 26S nuclear proteasomes, thereby decreasing their proteolytic activity. Recruited to the 19S regulatory particle of the 26S proteasome through its interaction with 19S component PSMD2/RPN1. Once recruited, dephosphorylates 19S component PSMC2/RPT1 which impairs PSMC2 ATPase activity and disrupts 26S proteasome assembly. Has also been reported to stimulate the proteolytic activity of the 26S proteasome.
Subcellular locations: Nucleus
Colocalizes with nuclear proteasomes.