E3 ubiquitin-protein ligase which accepts ubiquitin from an E2 ubiquitin-conjugating enzyme in the form of a thioester and then directly transfers the ubiquitin to targeted substrates . Catalyzes monoubiquitination of 26S proteasome subunit PSMC2/RPT1 .
Widely expressed, with highest levels in liver and heart and lowest levels in brain and skeletal muscle. Expressed in platelets (at protein level).