Focused refinement of RPN1 and the C-terminal helix of midnolin in the substrate-engaged human 26S proteasome. Determined by electron microscopy at 2.83 Å resolution. Released 25 Mar 2026.
Explore 9MBO in 3D Show helices and sheets RCSB PDB PDBe
9MBO contains 52 α-helices and 13 β-strands across 2 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.
| Element | Residues | Length | Sheet |
|---|---|---|---|
| α-helix | 378-411 | 34 |
| Element | Residues | Length | Sheet |
|---|---|---|---|
| α-helix | 47-63 | 17 | |
| α-helix | 71-87 | 17 | |
| α-helix | 100-102 | 3 | |
| α-helix | 103-112 | 10 | |
| α-helix | 114 | 1 | |
| α-helix | 117-130 | 14 | |
| α-helix | 141-144 | 4 | |
| α-helix | 151-154 | 4 | |
| α-helix | 156-172 | 17 | |
| α-helix | 181-197 | 17 | |
| α-helix | 201-210 | 10 | |
| α-helix | 214-216 | 3 | |
| α-helix | 226-235 | 10 | |
| α-helix | 244-258 | 15 | |
| α-helix | 262-272 | 11 | |
| α-helix | 275-283 | 9 | |
| α-helix | 288-301 | 14 | |
| α-helix | 314-321 | 8 | |
| α-helix | 326-337 | 12 | |
| α-helix | 346-349 | 4 | |
| α-helix | 351-353 | 3 | |
| α-helix | 368-381 | 14 | |
| α-helix | 395-399 | 5 | |
| α-helix | 405-411 | 7 | |
| α-helix | 413-417 | 5 | |
| α-helix | 422-428 | 7 | |
| α-helix | 438-451 | 14 | |
| α-helix | 475-488 | 14 | |
| α-helix | 495-501 | 7 | |
| α-helix | 502-504 | 3 | |
| α-helix | 512-525 | 14 | |
| α-helix | 532-543 | 12 | |
| α-helix | 553-556 | 4 | |
| α-helix | 557-565 | 9 | |
| α-helix | 571-573 | 3 | |
| α-helix | 574-579 | 6 | |
| α-helix | 585-599 | 15 | |
| α-helix | 606-616 | 11 | |
| α-helix | 650-660 | 11 | |
| α-helix | 665-680 | 16 | |
| α-helix | 684-687 | 4 | |
| α-helix | 690-697 | 8 | |
| α-helix | 704-713 | 10 | |
| α-helix | 719-732 | 14 | |
| α-helix | 739-751 | 13 | |
| α-helix | 756-769 | 14 | |
| α-helix | 771-774 | 4 | |
| β-strand | 776-777 | 2 | 1 |
| β-strand | 781-782 | 2 | 2 |
| β-strand | 787-788 | 2 | 2 |
| α-helix | 790-802 | 13 | |
| α-helix | 803-805 | 3 | |
| α-helix | 806-813 | 8 | |
| α-helix | 815-824 | 10 | |
| β-strand | 826-827 | 2 | 1 |
| β-strand | 830-833 | 4 | 3 |
| β-strand | 839 | 1 | 3 |
| β-strand | 843-850 | 8 | 4 |
| β-strand | 861-869 | 9 | 4 |
| β-strand | 872 | 1 | 3 |
| β-strand | 878-882 | 5 | 4 |
| β-strand | 887-889 | 3 | 5 |
| β-strand | 896-899 | 4 | 3 |
| β-strand | 900-902 | 3 | 5 |
| Molecule | Chains | Type | Length | Organism | UniProt |
|---|---|---|---|---|---|
| Midnolin | A | protein | 468 | Homo sapiens | Q504T8 (AlphaFold model) |
| 26S proteasome non-ATPase regulatory subunit 2 | B | protein | 908 | Homo sapiens | Q13200 (AlphaFold model) |
>9MBO_1 Midnolin (chains A) MEPQPGGARSCRRGAPGGACELGPAAEAAPMSLAIHSTTGTRYDLAVPPDETVEGLRKRL SQRLKVPKERLALLHKDTRLSSGKLQEFGVGDGSKLTLVPTVEAGLMSQASRPEQSVMQA LESLTETQVSDFLSGRSPLTLALRVGDHMMFVQLQLAAQHAPLQHRHVLAAAAAAAAARG DPSIASPVSSPCRPVSSAARVPPVPTSPSPASPSPITAGSFRSHAASTTCPEQMDCSPTA SSSASPGASTTSTPGASPAPRSRKPGAVIESFVNHAPGVFSGTFSGTLHPNCQDSSGRPR RDIGTILQILNDLLSATRHYQGMPPSLAQLRCHAQCSPASPAPDLAPRTTSCEKLTAAPS ASLLQGQSQIRMCKPPGDRLRQTENRATRCKVERLQLLLQQKRLRRKARRDARGPYHWSP SRKAGRSDSSSSGGGGSPSEASGLGLDFEDSVWKPEVNPDIKSEFVVA
>9MBO_2 26S proteasome non-ATPase regulatory subunit 2 (chains B) MEEGGRDKAPVQPQQSPAAAPGGTDEKPSGKERRDAGDKDKEQELSEEDKQLQDELEMLV ERLGEKDTSLYRPALEELRRQIRSSTTSMTSVPKPLKFLRPHYGKLKEIYENMAPGENKR FAADIISVLAMTMSGERECLKYRLVGSQEELASWGHEYVRHLAGEVAKEWQELDDAEKVQ REPLLTLVKEIVPYNMAHNAEHEACDLLMEIEQVDMLEKDIDENAYAKVCLYLTSCVNYV PEPENSALLRCALGVFRKFSRFPEALRLALMLNDMELVEDIFTSCKDVVVQKQMAFMLGR HGVFLELSEDVEEYEDLTEIMSNVQLNSNFLALARELDIMEPKVPDDIYKTHLENNRFGG SGSQVDSARMNLASSFVNGFVNAAFGQDKLLTDDGNKWLYKNKDHGMLSAAASLGMILLW DVDGGLTQIDKYLYSSEDYIKSGALLACGIVNSGVRNECDPALALLSDYVLHNSNTMRLG SIFGLGLAYAGSNREDVLTLLLPVMGDSKSSMEVAGVTALACGMIAVGSCNGDVTSTILQ TIMEKSETELKDTYARWLPLGLGLNHLGKGEAIEAILAALEVVSEPFRSFANTLVDVCAY AGSGNVLKVQQLLHICSEHFDSKEKEEDKDKKEKKDKDKKEAPADMGAHQGVAVLGIALI AMGEEIGAEMALRTFGHLLRYGEPTLRRAVPLALALISVSNPRLNILDTLSKFSHDADPE VSYNSIFAMGMVGSGTNNARLAAMLRQLAQYHAKDPNNLFMVRLAQGLTHLGKGTLTLCP YHSDRQLMSQVAVAGLLTVLVSFLDVRNIILGKSHYVLYGLVAAMQPRMLVTFDEELRPL PVSVRVGQAVDVVGQAGKPKTITGFQTHTTPVLLAHGERAELATEEFLPVTPILEGFVIL RKNPNYDL
Structural dynamics of the midnolin-proteasome during ubiquitin-independent substrate turnover. Zhu, C., Qin, L., Dai, Z. et al. Nat Commun (2026) 17. DOI 10.1038/s41467-026-71002-0 · PubMed
Other PDB entries of the same protein (UniProt Q504T8 (AlphaFold model), which also has an AlphaFold model), best resolution first:
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