9QON: 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 the alpha subunits, Ipo-9 and Ak2. Determined by electron microscopy at 3.2 Å resolution. Released 28 Jan 2026.
- Method
- Electron microscopy
- Resolution
- 3.2 Å
- Organism
- Homo sapiens
- Chains
- 11
- Atoms
- 16,534
- Mol. weight
- 378.96 kDa
- Released
- 28 Jan 2026
Explore 9QON in 3D
Show helices and sheets
RCSB PDB
PDBe
Secondary structure: helices and β-sheets
9QON contains 104 α-helices and 107 β-strands across 11 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: 22 helices, 6 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 697-703 | 7 | |
| α-helix | 707-730 | 24 | |
| β-strand | 732 | 1 | 1 |
| β-strand | 738 | 1 | 1 |
| α-helix | 739-750 | 12 | |
| α-helix | 757-760 | 4 | |
| α-helix | 763-773 | 11 | |
| α-helix | 775-778 | 4 | |
| α-helix | 779-781 | 3 | |
| α-helix | 782-795 | 14 | |
| α-helix | 799-814 | 16 | |
| α-helix | 817-826 | 10 | |
| β-strand | 828 | 1 | 2 |
| β-strand | 834 | 1 | 2 |
| α-helix | 835-844 | 10 | |
| α-helix | 847-849 | 3 | |
| α-helix | 853-873 | 21 | |
| β-strand | 882 | 1 | 3 |
| β-strand | 912 | 1 | 3 |
| α-helix | 913-928 | 16 | |
| α-helix | 929-931 | 3 | |
| α-helix | 994-996 | 3 | |
| α-helix | 998-1001 | 4 | |
| α-helix | 1004-1009 | 6 | |
| α-helix | 1012-1015 | 4 | |
| α-helix | 1020-1024 | 5 | |
| α-helix | 1025-1027 | 3 | |
| α-helix | 1030-1038 | 9 | |
Chain B: 1 helix, 1 β-strand
| Element | Residues | Length | Sheet |
|---|
| α-helix | 144-193 | 50 | |
| β-strand | 201 | 1 | 4 |
Chain C: 5 helices, 0 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 78-92 | 15 | |
| α-helix | 93-96 | 4 | |
| α-helix | 144-184 | 41 | |
| α-helix | 185-189 | 5 | |
| α-helix | 195-197 | 3 | |
Chain D: 2 helices, 0 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 70-72 | 3 | |
| α-helix | 78-95 | 18 | |
Chain F: 11 helices, 14 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 21-32 | 12 | |
| α-helix | 34-35 | 2 | |
| β-strand | 36-40 | 5 | 5 |
| β-strand | 44-52 | 9 | 5 |
| β-strand | 58 | 1 | 6 |
| α-helix | 59 | 1 | |
| β-strand | 66-68 | 3 | 7 |
| β-strand | 74-79 | 6 | 7 |
| α-helix | 81-102 | 22 | |
| α-helix | 105-107 | 3 | |
| α-helix | 108-121 | 14 | |
| β-strand | 125 | 1 | 8 |
| β-strand | 128 | 1 | 9 |
| β-strand | 133-139 | 7 | 7 |
| β-strand | 147-151 | 5 | 7 |
| β-strand | 159 | 1 | 7 |
| β-strand | 160 | 1 | 10 |
| β-strand | 162-165 | 4 | 5 |
| α-helix | 169-176 | 8 | |
| α-helix | 181-183 | 3 | |
| α-helix | 186-199 | 14 | |
| β-strand | 209-217 | 9 | 5 |
| β-strand | 225-226 | 2 | 5 |
| α-helix | 227-228 | 2 | |
| α-helix | 229-241 | 13 | |
Chain G: 11 helices, 16 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 9-11 | 3 | |
| α-helix | 23-31 | 9 | |
| α-helix | 32-35 | 4 | |
| β-strand | 38-43 | 6 | 11 |
| β-strand | 47-53 | 7 | 11 |
| β-strand | 61 | 1 | 10 |
| β-strand | 69 | 1 | 12 |
| β-strand | 73 | 1 | 13 |
| β-strand | 76 | 1 | 13 |
| β-strand | 79-82 | 4 | 12 |
| α-helix | 84-105 | 22 | |
| α-helix | 108-110 | 3 | |
| α-helix | 111-125 | 15 | |
| β-strand | 128 | 1 | 14 |
| β-strand | 131 | 1 | 8 |
| α-helix | 132-134 | 3 | |
| β-strand | 136-144 | 9 | 12 |
| β-strand | 148-154 | 7 | 12 |
| β-strand | 160-162 | 3 | 12 |
| β-strand | 163 | 1 | 15 |
| β-strand | 165-169 | 5 | 11 |
| α-helix | 172-184 | 13 | |
| α-helix | 191-206 | 16 | |
| β-strand | 215-221 | 7 | 11 |
| β-strand | 228-229 | 2 | 11 |
| α-helix | 230-231 | 2 | |
| α-helix | 232-242 | 11 | |
Chain O: 10 helices, 17 β-strands
| Element | Residues | Length | Sheet |
|---|
| β-strand | 8 | 1 | 16 |
| β-strand | 12-13 | 2 | 17 |
| β-strand | 17-18 | 2 | 17 |
| α-helix | 19-29 | 11 | |
| β-strand | 34-38 | 5 | 18 |
| β-strand | 43-47 | 5 | 18 |
| β-strand | 56 | 1 | 15 |
| β-strand | 65-66 | 2 | 19 |
| β-strand | 71-77 | 7 | 19 |
| α-helix | 80-100 | 21 | |
| α-helix | 103-105 | 3 | |
| α-helix | 106-119 | 14 | |
| β-strand | 124 | 1 | 16 |
| β-strand | 126 | 1 | 14 |
| α-helix | 127-129 | 3 | |
| β-strand | 131-138 | 8 | 19 |
| β-strand | 143-148 | 6 | 19 |
| β-strand | 154-156 | 3 | 19 |
| β-strand | 157 | 1 | 20 |
| β-strand | 159-162 | 4 | 18 |
| α-helix | 166-176 | 11 | |
| α-helix | 183-195 | 13 | |
| α-helix | 204-206 | 3 | |
| β-strand | 210-213 | 4 | 18 |
| β-strand | 216-219 | 4 | 18 |
| α-helix | 220-221 | 2 | |
| α-helix | 222-230 | 9 | |
Chain P: 10 helices, 12 β-strands
| Element | Residues | Length | Sheet |
|---|
| α-helix | 19-28 | 10 | |
| α-helix | 32-33 | 2 | |
| β-strand | 34-39 | 6 | 21 |
| β-strand | 42-48 | 7 | 21 |
| β-strand | 56 | 1 | 20 |
| β-strand | 65-67 | 3 | 22 |
| β-strand | 72-78 | 7 | 22 |
| α-helix | 80-101 | 22 | |
| α-helix | 104-106 | 3 | |
| α-helix | 107-120 | 14 | |
| α-helix | 128-130 | 3 | |
| β-strand | 132-140 | 9 | 22 |
| β-strand | 144-150 | 7 | 22 |
| β-strand | 156-158 | 3 | 22 |
| β-strand | 159 | 1 | 23 |
| β-strand | 161-164 | 4 | 21 |
| α-helix | 168-178 | 11 | |
| α-helix | 186-200 | 15 | |
| α-helix | 208-210 | 3 | |
| β-strand | 211-219 | 9 | 21 |
| β-strand | 222-227 | 6 | 21 |
| α-helix | 230-245 | 16 | |
3 more chain groups are not listed. Open the entry in the viewer and use the sequence panel to see them.
Molecules and chains
| Molecule | Chains | Type | Length | Organism | UniProt |
|---|
| Importin-9 | A | protein | 1041 | Homo sapiens | Q96P70 (AlphaFold model) |
| Akirin-2 | B, C, D | protein | 203 | Homo sapiens | Q53H80 (AlphaFold model) |
| Proteasome subunit alpha type-3 | F | protein | 255 | Homo sapiens | P25788 (AlphaFold model) |
| Proteasome subunit alpha type-6 | G | protein | 246 | Homo sapiens | P60900 (AlphaFold model) |
| Proteasome subunit alpha type-2 | O | protein | 234 | Homo sapiens | P25787 |
| Proteasome subunit alpha type-4 | P | protein | 261 | Homo sapiens | P25789 |
| Proteasome subunit alpha type-7 | Q | protein | 248 | Homo sapiens | O14818 |
| Proteasome subunit alpha type-5 | R | protein | 241 | Homo sapiens | P28066 |
| Proteasome subunit alpha type-1 | S | protein | 263 | Homo sapiens | P25786 |
Sequence of entity 1 (A), FASTA
>9QON_1 Importin-9 (chains A)
MAAAAAAGAASGLPGPVAQGLKEALVDTLTGILSPVQEVRAAAEEQIKVLEVTEEFGVHL
AELTVDPQGALAIRQLASVILKQYVETHWCAQSEKFRPPETTERAKIVIRELLPNGLRES
ISKVRSSVAYAVSAIAHWDWPEAWPQLFNLLMEMLVSGDLNAVHGAMRVLTEFTREVTDT
QMPLVAPVILPEMYKIFTMAEVYGIRTRSRAVEIFTTCAHMICNMEELEKGAAKVLIFPV
VQQFTEAFVQALQIPDGPTSDSGFKMEVLKAVTALVKNFPKHMVSSMQQILPIVWNTLTE
SAAFYVRTEVNYTEEVEDPVDSDGEVLGFENLVFSIFEFVHALLENSKFKSTVKKALPEL
IYYIILYMQITEEQIKVWTANPQQFVEDEDDDTFSYTVRIAAQDLLLAVATDFQNESAAA
LAAAATRHLQEAEQTKNSGTEHWWKIHEACMLALGSVKAIITDSVKNGRIHFDMHGFLTN
VILADLNLSVSPFLLGRALWAASRFTVAMSPELIQQFLQATVSGLHETQPPSVRISAVRA
IWGYCDQLKVSESTHVLQPFLPSILDGLIHLAAQFSSEVLNLVMETLCIVCTVDPEFTAS
MESKICPFTIAIFLKYSNDPVVASLAQDIFKELSQIEACQGPMQMRLIPTLVSIMQAPAD
KIPAGLCATAIDILTTVVRNTKPPLSQLLICQAFPAVAQCTLHTDDNATMQNGGECLRAY
VSVTLEQVAQWHDEQGHNGLWYVMQVVSQLLDPRTSEFTAAFVGRLVSTLISKAGRELGE
NLDQILRAILSKMQQAETLSVMQSLIMVFAHLVHTQLEPLLEFLCSLPGPTGKPALEFVM
AEWTSRQHLFYGQYEGKVSSVALCKLLQHGINADDKRLQDIRVKGEEIYSMDEGIRTRSK
SAKNPERWTNIPLLVKILKLIINELSNVMEANAARQATPAEWSQDDSNDMWEDQEEEEEE
EEDGLAGQLLSDILATSKYEEDYYEDDEEDDPDALKDPLYQIDLQAYLTDFLCQFAQQPC
YIMFSGHLNDNERRVLQTIGI
Sequence of entity 2 (B, C, D), FASTA
>9QON_2 Akirin-2 (chains B, C, D)
MACGATLKRTLDFDPLLSPASPKRRRCAPLSAPTSAAASPLSAAAATAASFSAAAASPQK
YLRMEPSPFGDVSSRLTTEQILYNIKQEYKRMQKRRHLETSFQQTDPCCTSDAQPHAFLL
SGPASPGTSSAASSPLKKEQPLFTLRQVGMICERLLKEREEKVREEYEEILNTKLAEQYD
AFVKFTHDQIMRRYGEQPASYVS
Sequence of entity 3 (F), FASTA
>9QON_3 Proteasome subunit alpha type-3 (chains F)
MSSIGTGYDLSASTFSPDGRVFQVEYAMKAVENSSTAIGIRCKDGVVFGVEKLVLSKLYE
EGSNKRLFNVDRHVGMAVAGLLADARSLADIAREEASNFRSNFGYNIPLKHLADRVAMYV
HAYTLYSAVRPFGCSFMLGSYSVNDGAQLYMIDPSGVSYGYWGCAIGKARQAAKTEIEKL
QMKEMTCRDIVKEVAKIIYIVHDEVKDKAFELELSWVGELTNGRHEIVPKDIREEAEKYA
KESLKEEDESDDDNM
Sequence of entity 4 (G), FASTA
>9QON_4 Proteasome subunit alpha type-6 (chains G)
MSRGSSAGFDRHITIFSPEGRLYQVEYAFKAINQGGLTSVAVRGKDCAVIVTQKKVPDKL
LDSSTVTHLFKITENIGCVMTGMTADSRSQVQRARYEAANWKYKYGYEIPVDMLCKRIAD
ISQVYTQNAEMRPLGCCMILIGIDEEQGPQVYKCDPAGYYCGFKATAAGVKQTESTSFLE
KKVKKKFDWTFEQTVETAITCLSTVLSIDFKPSEIEVGVVTVENPKFRILTEAEIDAHLV
ALAERD
Sequence of entity 5 (O), FASTA
>9QON_5 Proteasome subunit alpha type-2 (chains O)
MAERGYSFSLTTFSPSGKLVQIEYALAAVAGGAPSVGIKAANGVVLATEKKQKSILYDER
SVHKVEPITKHIGLVYSGMGPDYRVLVHRARKLAQQYYLVYQEPIPTAQLVQRVASVMQE
YTQSGGVRPFGVSLLICGWNEGRPYLFQSDPSGAYFAWKATAMGKNYVNGKTFLEKRYNE
DLELEDAIHTAILTLKESFEGQMTEDNIEVGICNEAGFRRLTPTEVKDYLAAIA
Sequence of entity 6 (P), FASTA
>9QON_6 Proteasome subunit alpha type-4 (chains P)
MSRRYDSRTTIFSPEGRLYQVEYAMEAIGHAGTCLGILANDGVLLAAERRNIHKLLDEVF
FSEKIYKLNEDMACSVAGITSDANVLTNELRLIAQRYLLQYQEPIPCEQLVTALCDIKQA
YTQFGGKRPFGVSLLYIGWDKHYGFQLYQSDPSGNYGGWKATCIGNNSAAAVSMLKQDYK
EGEMTLKSALALAIKVLNKTMDVSKLSAEKVEIATLTRENGKTVIRVLKQKEVEQLIKKH
EEEEAKAEREKKEKEQKEKDK
Sequence of entity 7 (Q), FASTA
>9QON_7 Proteasome subunit alpha type-7 (chains Q)
MSYDRAITVFSPDGHLFQVEYAQEAVKKGSTAVGVRGRDIVVLGVEKKSVAKLQDERTVR
KICALDDNVCMAFAGLTADARIVINRARVECQSHRLTVEDPVTVEYITRYIASLKQRYTQ
SNGRRPFGISALIVGFDFDGTPRLYQTDPSGTYHAWKANAIGRGAKSVREFLEKNYTDEA
IETDDLTIKLVIKALLEVVQSGGKNIELAVMRRDQSLKILNPEEIEKYVAEIEKEKEENE
KKKQKKAS
Sequence of entity 8 (R), FASTA
>9QON_8 Proteasome subunit alpha type-5 (chains R)
MFLTRSEYDRGVNTFSPEGRLFQVEYAIEAIKLGSTAIGIQTSEGVCLAVEKRITSPLME
PSSIEKIVEIDAHIGCAMSGLIADAKTLIDKARVETQNHWFTYNETMTVESVTQAVSNLA
LQFGEEDADPGAMSRPFGVALLFGGVDEKGPQLFHMDPSGTFVQCDARAIGSASEGAQSS
LQEVYHKSMTLKEAIKSSLIILKQVMEEKLNATNIELATVQPGQNFHMFTKEELEEVIKD
I
Sequence of entity 9 (S), FASTA
>9QON_9 Proteasome subunit alpha type-1 (chains S)
MFRNQYDNDVTVWSPQGRIHQIEYAMEAVKQGSATVGLKSKTHAVLVALKRAQSELAAHQ
KKILHVDNHIGISIAGLTADARLLCNFMRQECLDSRFVFDRPLPVSRLVSLIGSKTQIPT
QRYGRRPYGVGLLIAGYDDMGPHIFQTCPSANYFDCRAMSIGARSQSARTYLERHMSEFM
ECNLNELVKHGLRALRETLPAEQDLTTKNVSIGIVGKDLEFTIYDDDDVSPFLEGLEERP
QRKAQPAQPADEPAEKADEPMEH
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 Q96P70 (AlphaFold model), which also has an AlphaFold model), best resolution first:
- 6N1Z 2.7 Å, Importin-9 bound to H2A-H2B
- 9QOO 3.3 Å, Composite model: Ternary complex of the human 20S proteasome in complex with Importin-9…
- 10SM 3.5 Å, Importin-9 bound to ETS homologous factor (EHF)
- 9QOP 3.7 Å, Binary complex of human Importin-9 with one homodimer of Akirin-2
- 8F7A 3.78 Å, Cryo-EM structure of Importin-9 bound to RanGTP
- 9QNO 4.2 Å, Ternary complex of the human 20S proteasome in complex with Importin-9 and two…
Browse structure collections
About this viewer
MolViewer shows 9QON directly in your browser with nothing to install. Switch between cartoon, ball-and-stick, spacefill and surface views, color by chain, secondary structure or B-factor, measure distances, angles and dihedrals, and share or embed the view.