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. Interacts with Rpn6. Expressed during embryonic stages 11-14 in the muscle attachment sites (apodemes); pharynx attachment to the roof of the mouth and in the epidermis of the head for the dorsal and ventral prothoracic pharyngeal muscle attachment. From stage 16 onwards expression is seen in all thoracic and abdominal apodemes. Expressed both maternally with high levels during oogenesis, and zygotically. Belongs to the CSN2 family.