Essential component of the COP9 signalosome complex (CSN), a complex involved in various cellular and developmental processes. The CSN complex is an essential regulator of the ubiquitin (Ubl) conjugation pathway by mediating the deneddylation of the cullin subunits of the SCF-type E3 ligase complexes, leading to decrease the Ubl ligase activity of SCF. The CSN complex plays an essential role in embryogenesis and oogenesis and is required to regulate microtubule stability in the early embryo. Mediates mei-3/katanin targeting for degradation at the meiosis to mitosis transition via deneddylation of cul-3. Component of the CSN complex, probably composed of csn-1, csn-2, csn-3, csn-4, csn-5, csn-6 and csn-7. Within the complex it probably interacts directly with csn-2, csn-4 and csn-5. May interact with itself. Interacts with rbx-1. Belongs to the CSN1 family.