Protease that catalyzes two essential functions in the SUMO pathway: processing of full-length SUMO3 to its mature form and deconjugation of SUMO2 and SUMO3 from targeted proteins. Has weak proteolytic activity against full-length SUMO1 or SUMO1 conjugates. Required for cell division. Interacts with CCAR2. Belongs to the peptidase C48 family. Truncated N-terminus.