Protein Domain : COP9 signalosome subunit 6 IPR033859

Type	Family
Description	The COP9 signalosome (CSN) is a conserved protein complex that regulates the ubiquitin (Ubl) conjugation pathway by mediating the deneddylation of the cullin subunits of SCF-type E3 ligase complexes [ ], which leads to a decrease in Ubl ligase activity of SCF-type complexes such as SCF, CSA or DDB2 []. Protein kinases CK2 and D, which phosphorylate proteins such as cJun and p53 resulting in their degradation by the ubiquitin-26S proteasome system, also binds to CSN [, ]. The mammalian CSN typically consistis of eight subunits designated CSN1-CSN8. The fission yeast possesses a smaller version of the CSN, consisting only of six subunits, whereas a more distant CSN-like complex has been described in Saccharomyces cerevisiae [].CSN6 (COP9 signalosome subunit 6; COP9 subunit 6; MOV34 homolog, 34 kD; MEROPS identifier M67.972) is one of the eight subunits of COP9 signalosome. CSN6 is an MPN-domain protein that directly interacts with the MPN+-domain subunit CSN5 [ ]. It is cleaved during apoptosis by activated caspases. CSN6 processing occurs in CSN/CRL (cullin-RING Ub ligase) complexes and is followed by the cleavage of Rbx1, the direct interaction partner of CSN6 []. CSN6 cleavage enhances CSN-mediated deneddylating activity (i.e. cleavage of ubiquitin-like protein Nedd8 (neural precursor cell expressed, developmentally downregulated 8)) in the cullin 1 in cells []. The cleavage of Rbx1 and increased deneddylation of cullins inactivate CRLs and presumably stabilize pro-apoptotic factors for final apoptotic steps. While CSN6 shows a typical MPN metalloprotease fold, it lacks the canonical JAMM motif, and therefore does not show catalytic isopeptidase activity.
Short Name	MPN_CSN6