{PDOC50250}
{PS50250; PCI}
{BEGIN}
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* PCI domain profile *
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The PCI  (for  Proteasome,  COP9,  Initiation factor 3) domain (sometimes also
referred to  as  the  PINT  domain, for Proteasome subunits, Int-6, Nip-1, and
Trip-15)  is present  in  six  different  subunits  of 26 proteasome lid, COP9
signalosome (CSN)   and  eukaryotic  translation  initiation  factor-3  (eIF3)
complexes, as well as in subunits of certain other multiprotein complexes. The
PCI domain  mediates  and  stabilizes  protein-protein interactions within the
complexes. The  role  of the PCI domains is most likely that of a scaffold for
the other  complex  subunits  and other binding partners. The PCI domain could
play a   role   as   a   universal  binding  domain  supporting  intra-complex
interactions as well as recruitments of additional ligands [1,2,3,4,5,6].

PCI is  an ~190-amino acid domain, not well conserved in its primary sequence,
usually located  near  the  C-terminus of the protein. It does not contain any
invariant residues  or  any  conserved  pattern of charged residues that would
suggest a  catalytic  activity.  The PCI domain is comprised of two subdomains
that are intimately connected, an N-terminal helical bundle (HB) subdomain and
a C-terminal  globular  winged  helix  (WH) subdomain (see <PDB:3CHM>). The C-
terminal half  of  the PCI domain is much better conserved than the N-terminal
halfdomain [4,5,6].

Some proteins known to contain a PCI domain are listed below:

 - Eukaryotic 26S proteasome non-ATPase regulatory subunit 3 (PSMD3).
 - Eukaryotic 26S proteasome non-ATPase regulatory subunit 6 (PSMD6).
 - Eukaryotic 26S proteasome non-ATPase regulatory subunit 8 (PSMD8).
 - Eukaryotic 26S proteasome non-ATPase regulatory subunit 11 (PSMD11)
 - Eukaryotic 26S proteasome non-ATPase regulatory subunit 12 (PSMD12).
 - Eukaryotic 26S proteasome non-ATPase regulatory subunit 13 (PSMD13).
 - Eukaryotic COP9 signalosome complex subunit 1 (CSN1).
 - Eukaryotic COP9 signalosome complex subunit 2 (CSN2).
 - Eukaryotic COP9 signalosome complex subunit 3 (CSN3).
 - Eukaryotic COP9 signalosome complex subunit 4 (CSN4).
 - Eukaryotic COP9 signalosome complex subunit 7 (CSN7).
 - Eukaryotic COP9 signalosome complex subunit 8 (CSN8).
 - Eukaryotic translation initiation factor 3 subunit A (EIF3A).
 - Eukaryotic translation initiation factor 3 subunit C (EIF3C).
 - Eukaryotic translation initiation factor 3 subunit E (EIF3E).
 - Eukaryotic translation initiation factor 3 subunit K (EIF3K).
 - Eukaryotic translation initiation factor 3 subunit L (EIF3L).
 - Eukaryotic translation initiation factor 3 subunit M (EIF3M).
 - Eukaryotic  PCI  domain-containing  protein  2  (PCID2), a component of the
   transcription and  export  complex  2  (TREX-2  complex)  that functions in
   docking export-competent ribonucleoprotein particles (mRNPs) to the nuclear
   entrance of the nuclear pore complex (nuclear basket).
 - Eukaryotic  germinal-center  associated nuclear protein (GANP), a component
   of the  transcription  and export complex 2 (TREX-2 complex) that functions
   in docking  export-competent  ribonucleoprotein  particles  (mRNPs)  to the
   nuclear entrance of the nuclear pore complex (nuclear basket).

The profile we developed covers the entire PCI domain.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: July 2017 / First entry.

[ 1] Hofmann K., Bucher P.
     "The PCI domain: a common theme in three multiprotein complexes."
     Trends Biochem. Sci. 23:204-205(1998).
     PubMed=9644972
[ 2] Aravind L., Ponting C.P.
     "Homologues of 26S proteasome subunits are regulators of transcription
     and translation."
     Protein Sci. 7:1250-1254(1998).
     PubMed=9605331; DOI=10.1002/pro.5560070521
[ 3] Scheel H., Hofmann K.
     "Prediction of a common structural scaffold for proteasome lid,
     COP9-signalosome and eIF3 complexes."
     BMC Bioinformatics. 6:71-71(2005).
     PubMed=15790418; DOI=10.1186/1471-2105-6-71
[ 4] Lee J.-H., Yi L., Li J., Schweitzer K., Borgmann M., Naumann M., Wu H.
     "Crystal structure and versatile functional roles of the COP9
     signalosome subunit  1."
     Proc. Natl. Acad. Sci. U. S. A. 110:11845-11850(2013).
     PubMed=23818606; DOI=10.1073/pnas.1302418110
[ 5] Wei Z., Zhang P., Zhou Z., Cheng Z., Wan M., Gong W.
     "Crystal structure of human eIF3k, the first structure of eIF3
     subunits."
     J. Biol. Chem. 279:34983-34990(2004).
     PubMed=15180986; DOI=10.1074/jbc.M405158200
[ 6] Dessau M., Halimi Y., Erez T., Chomsky-Hecht O., Chamovitz D.A.,
     Hirsch J.A.
     "The Arabidopsis COP9 signalosome subunit 7 is a model PCI domain
     protein with subdomains involved in COP9 signalosome assembly."
     Plant Cell 20:2815-2834(2008).
     PubMed=18854373; DOI=10.1105/tpc.107.053801

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