Component of the COP9 signalosome (CSN) complex that acts as an regulator of the ubiquitin (Ubl) conjugation pathway by mediating the deneddylation of the cullin subunit of SCF-type E3 ubiquitin-protein ligase complexes. The CSN complex is involved in the regulation of the mating pheromone response (By similarity). Component of a COP9 signalosome-like (CSN) complex. Belongs to the CSN12 family.