The domain within your query sequence starts at position 300 and ends at position 398; the E-value for the PCI domain shown below is 1.3e-15.

PKYKDLLKLFTTMELMRWSTLVEDYGVELRKGSSETPATDVFSSTEEGEKRWKDLKSRVV
EHNIRIMAKYYTRITMKRMAQLLDLSVDVWTTQARPRRI

PCI

PCI
PFAM accession number:PF01399
Interpro abstract (IPR000717):

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 [(PUBMED:9644972), (PUBMED:9605331), (PUBMED:15790418), (PUBMED:23818606), (PUBMED:15180986), (PUBMED:18854373)].

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. The C- terminal half of the PCI domain is much better conserved than the N-terminal half [(PUBMED:23818606), (PUBMED:15180986), (PUBMED:18854373)].

This is a PFAM domain. For full annotation and more information, please see the PFAM entry PCI