COP9 signalosome (human), (purified)

Originally identified in Arabidopsis as a suppressor of light-dependent development and is essential for development in plants, and is itself both a target for kinase activity and associates with and coordinates activity of kinases. Although the CSN complex and the ‘lid’ of the 19S regulator of the 26S proteasome share significant structural similarities, their functions seem to be different and neither protein-protein interactions nor associated activities described for the CSN have been identified for the 19S‘lid’. The CSN appears to be a platform connecting signalling with degradation by the 26S proteasome.