Protein
COP9 signalosome complex subunit 5a
Organism
Arabidopsis thaliana
Function
Probable protease subunit of the COP9 signalosome complex (CSN), a complex involved in various cellular and developmental processes such as photomorphogenesis and auxin and jasmonate responses. 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. In the complex, it probably acts as the catalytic center that mediates the cleavage of Nedd8 from cullins. It however has no metalloprotease activity by itself and requires the other subunits of the CSN complex (By similarity). The CSN complex is involved in repression of photomorphogenesis in darkness by regulating the activity of COP1-containing Ubl ligase complexes. The complex is also required for degradation of PSIAA6 by regulating the activity of the Ubl ligase SCF-TIR complex. Involved in CSN's deneddylation/derubylation activity (PubMed:15486099). Required for the deneddylation of all cullins (PubMed:15923347, PubMed:17307927). Essential for the structural integrity of the CSN holocomplex (PubMed:17307927).
Similarity
Belongs to the peptidase M67A family. CSN5 subfamily.
Sequence
MEGSSSAIARKTWELENNILPVEPTDSASDSIFHYDDASQAKIQQEKPWASDPNYFKRVHISALALLKMVVHARSGGTIEIMGLMQGKTEGDTIIVMDAFALPVEGTETRVNAQSDAYEYMVEYSQTSKLAGRLENVVGWYHSHPGYGCWLSGIDVSTQMLNQQYQEPFLAVVIDPTRTVSAGKVEIGAFRTYPEGHKISDDHVSEYQTIPLNKIEDFGVHCKQYYSLDITYFKSSLDSHLLDLLWNKYWVNTLSSSPLLGNGDYVAGQISDLAEKLEQAESQLANSRYGGIAPAGHQRRKEDEPQLAKITRDSAKITVEQVHGLMSQVIKDILFNSARQSKKSADDSSDPEPMITS