9QNO: Ternary complex of the human 20S proteasome

Ternary complex of the human 20S proteasome in complex with Importin-9 and two homodimers of Akirin-2 - focussed refinement on Importin-9 and Akirin-2. Determined by electron microscopy at 4.2 Å resolution. Released 28 Jan 2026.

Method
Electron microscopy
Resolution
4.2 Å
Organism
Homo sapiens
Chains
3
Atoms
3,965
Mol. weight
161.11 kDa
Released
28 Jan 2026

Explore 9QNO in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9QNO contains 55 α-helices and 4 β-strands across 3 chains. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.

Chain A: 53 helices, 2 β-strands

ElementResiduesLengthSheet
α-helix17-3216
α-helix37-5014
α-helix58-658
α-helix71-8818
α-helix100-1023
α-helix103-11210
α-helix114-1163
α-helix122-13716
α-helix146-15611
α-helix160-17617
α-helix182-19817
α-helix205-22218
α-helix226-2283
α-helix231-25222
β-strand25712
β-strand26012
α-helix262-27817
α-helix280-2823
α-helix284-30421
α-helix305-3073
α-helix331-34313
α-helix347-3493
α-helix352-3554
α-helix357-36711
α-helix370-3712
α-helix372-3798
α-helix382-3887
α-helix398-40912
α-helix412-4143
α-helix416-4183
α-helix419-43719
α-helix441-4477
α-helix450-4578
α-helix459-4679
α-helix474-4763
α-helix477-4826
α-helix483-4853
α-helix492-50514
α-helix506-5083
α-helix511-52313
α-helix531-54818
α-helix552-5576
α-helix561-57010
α-helix578-59316
α-helix595-6006
α-helix602-61514
α-helix620-63516
α-helix637-6393
α-helix640-65617
α-helix6631
α-helix666-68015
α-helix6821
α-helix685-6862
α-helix6871
α-helix688-6925
Chain D: 1 helix, 1 β-strand
ElementResiduesLengthSheet
β-strand14211
α-helix144-18441
Chain E: 1 helix, 1 β-strand
ElementResiduesLengthSheet
β-strand14211
α-helix144-18138

Molecules and chains

MoleculeChainsTypeLengthOrganismUniProt
Akirin-2D, Eprotein203Homo sapiensQ53H80 (AlphaFold model)
Importin-9Aprotein1041Homo sapiensQ96P70 (AlphaFold model)
Sequence of entity 1 (D, E), FASTA
>9QNO_1 Akirin-2 (chains D, E)
MACGATLKRTLDFDPLLSPASPKRRRCAPLSAPTSAAASPLSAAAATAASFSAAAASPQK
YLRMEPSPFGDVSSRLTTEQILYNIKQEYKRMQKRRHLETSFQQTDPCCTSDAQPHAFLL
SGPASPGTSSAASSPLKKEQPLFTLRQVGMICERLLKEREEKVREEYEEILNTKLAEQYD
AFVKFTHDQIMRRYGEQPASYVS
Sequence of entity 2 (A), FASTA
>9QNO_2 Importin-9 (chains A)
MAAAAAAGAASGLPGPVAQGLKEALVDTLTGILSPVQEVRAAAEEQIKVLEVTEEFGVHL
AELTVDPQGALAIRQLASVILKQYVETHWCAQSEKFRPPETTERAKIVIRELLPNGLRES
ISKVRSSVAYAVSAIAHWDWPEAWPQLFNLLMEMLVSGDLNAVHGAMRVLTEFTREVTDT
QMPLVAPVILPEMYKIFTMAEVYGIRTRSRAVEIFTTCAHMICNMEELEKGAAKVLIFPV
VQQFTEAFVQALQIPDGPTSDSGFKMEVLKAVTALVKNFPKHMVSSMQQILPIVWNTLTE
SAAFYVRTEVNYTEEVEDPVDSDGEVLGFENLVFSIFEFVHALLENSKFKSTVKKALPEL
IYYIILYMQITEEQIKVWTANPQQFVEDEDDDTFSYTVRIAAQDLLLAVATDFQNESAAA
LAAAATRHLQEAEQTKNSGTEHWWKIHEACMLALGSVKAIITDSVKNGRIHFDMHGFLTN
VILADLNLSVSPFLLGRALWAASRFTVAMSPELIQQFLQATVSGLHETQPPSVRISAVRA
IWGYCDQLKVSESTHVLQPFLPSILDGLIHLAAQFSSEVLNLVMETLCIVCTVDPEFTAS
MESKICPFTIAIFLKYSNDPVVASLAQDIFKELSQIEACQGPMQMRLIPTLVSIMQAPAD
KIPAGLCATAIDILTTVVRNTKPPLSQLLICQAFPAVAQCTLHTDDNATMQNGGECLRAY
VSVTLEQVAQWHDEQGHNGLWYVMQVVSQLLDPRTSEFTAAFVGRLVSTLISKAGRELGE
NLDQILRAILSKMQQAETLSVMQSLIMVFAHLVHTQLEPLLEFLCSLPGPTGKPALEFVM
AEWTSRQHLFYGQYEGKVSSVALCKLLQHGINADDKRLQDIRVKGEEIYSMDEGIRTRSK
SAKNPERWTNIPLLVKILKLIINELSNVMEANAARQATPAEWSQDDSNDMWEDQEEEEEE
EEDGLAGQLLSDILATSKYEEDYYEDDEEDDPDALKDPLYQIDLQAYLTDFLCQFAQQPC
YIMFSGHLNDNERRVLQTIGI

Primary citation

A multivalent adaptor mechanism drives the nuclear import of proteasomes. Brunner, H.L., Kalis, R.W., Grundmann, L. et al. Nat Commun (2026) 17. DOI 10.1038/s41467-026-69162-0 · PubMed

Other PDB entries of the same protein (UniProt Q53H80 (AlphaFold model), which also has an AlphaFold model), best resolution first:

Browse structure collections

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