The COP9 signalosome is an eight-subunit complex that is structurally and evolutionarily related to the 19S lid of the 26S proteasome. The COP9 signalosome plays a central role in the regulation of the E3-cullin RING ubiquitin ligases, deNEDDylating the cullin subunit via the isopeptidase activity of the CNS5 subunit. (Adapted from FBrf0225508 and FBrf0225509).
Notes on Group
COP9 is an acronym from Constitutive photomorphogenesis 9, derived from its identification in Arabidopsis as as a repressor of photomorphogenesis.
There are two alternative isoforms of the CSN1 subunit. High-throughput expression studies indicate that CSN1b is more ubiquitously expressed and CSN1a is testis-specific.
