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 oogenesis and embryogenesis and is required for proper photoreceptor R cell differentiation and promote lamina glial cell migration or axon targeting. It also promotes Ubl-dependent degradation of cyclin E (CycE) during early oogenesis. Component of the CSN complex, probably composed of CSN1b, alien/CSN2, CSN3, CSN4, CSN5, CSN6, CSN7 and CSN8. Belongs to the CSN1 family.