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 (By similarity). The CSN complex is involved in the regulation of the circadian clock through its control of the stability of the SCF(FWD1) complex. Component of the COP9 signalosome (CSN) complex. Belongs to the peptidase M67A family. CSN6 subfamily.