9N85: Importin subunit beta-1

Cryo-EM structure of human importin beta:Ran-GTP:RanBP1 trimeric complex. Determined by electron microscopy at 2.6 Å resolution. Released 10 Dec 2025.

Method: Electron microscopy
Resolution: 2.6 Å
Organism: Homo sapiens
Chains: 3
Atoms: 9,711
Mol. weight: 138.64 kDa
Ligands: MG, GTP
Released: 10 Dec 2025

Explore 9N85 in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9N85 contains 65 α-helices and 18 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: 52 helices, 0 β-strands

Element	Residues	Length
α-helix	3-8	6
α-helix	9-11	3
α-helix	15-31	17
α-helix	33-45	13
α-helix	51-63	13
α-helix	70-81	12
α-helix	85-96	12
α-helix	109-120	12
α-helix	121-123	3
α-helix	130-138	9
α-helix	144-160	17
α-helix	170-181	12
α-helix	188-200	13
α-helix	204-206	3
α-helix	208-210	3
α-helix	212-225	14
α-helix	231-247	17
α-helix	249-251	3
α-helix	253-255	3
α-helix	256-260	5
α-helix	261-268	8
α-helix	273-303	31
α-helix	314-329	16
α-helix	344-359	16
α-helix	360-363	4
α-helix	364-374	11
α-helix	380-392	13
α-helix	399-416	18
α-helix	422-438	17
α-helix	449-459	11
α-helix	464-483	20
α-helix	503-514	12
α-helix	521-523	3
α-helix	524-537	14
α-helix	544-555	12
α-helix	558-563	6
α-helix	587-595	9
α-helix	601-618	18
α-helix	625-636	12
α-helix	650-658	9
α-helix	665-681	17
α-helix	686-702	17
α-helix	709-721	13
α-helix	731-743	13
α-helix	755-776	22
α-helix	794-800	7
α-helix	801-803	3
α-helix	804-807	4
α-helix	814-829	16
α-helix	834-838	5
α-helix	842-850	9
α-helix	859-875	17

Chain B: 1 helix, 9 β-strands

Element	Residues	Length	Sheet
β-strand	37-51	15	1
β-strand	58-72	15	1
β-strand	78-80	3	1
β-strand	83	1	2
β-strand	90	1	2
β-strand	94-95	2	1
β-strand	103-105	3	1
β-strand	108-119	12	1
β-strand	126-133	8	1
α-helix	137-159	23

Chain C: 12 helices, 9 β-strands

Element	Residues	Length	Sheet
β-strand	10-17	8	3
α-helix	26-31	6
β-strand	45-54	10	3
β-strand	57-66	10	3
β-strand	85-91	7	3
α-helix	95-99	5
α-helix	101-109	9
β-strand	117-122	6	3
α-helix	124-126	3
α-helix	133-135	3
α-helix	138-142	5
β-strand	145-148	4	3
β-strand	150	1	4
β-strand	155	1	4
α-helix	159-165	7
α-helix	166-170	5
β-strand	176	1	3
α-helix	177-180	4
α-helix	182-185	4
α-helix	191-206	16
α-helix	208-210	3

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Importin subunit beta-1	A	protein	876	Homo sapiens	Q14974 (AlphaFold model)
Ran-specific GTPase-activating protein	B	protein	144	Homo sapiens	P43487 (AlphaFold model)
GTP-binding nuclear protein Ran	C	protein	210	Homo sapiens	P62826 (AlphaFold model)

Sequence of entity 1 (A), FASTA

>9N85_1 Importin subunit beta-1 (chains A)
MELITILEKTVSPDRLELEAAQKFLERAAVENLPTFLVELSRVLANPGNSQVARVAAGLQ
IKNSLTSKDPDIKAQYQQRWLAIDANARREVKNYVLHTLGTETYRPSSASQCVAGIACAE
IPVNQWPELIPQLVANVTNPNSTEHMKESTLEAIGYICQDIDPEQLQDKSNEILTAIIQG
MRKEEPSNNVKLAATNALLNSLEFTKANFDKESERHFIMQVVCEATQCPDTRVRVAALQN
LVKIMSLYYQYMETYMGPALFAITIEAMKSDIDEVALQGIEFWSNVCDEEMDLAIEASEA
AEQGRPPEHTSKFYAKGALQYLVPILTQTLTKQDENDDDDDWNPCKAAGVCLMLLATCCE
DDIVPHVLPFIKEHIKNPDWRYRDAAVMAFGCILEGPEPSQLKPLVIQAMPTLIELMKDP
SVVVRDTAAWTVGRICELLPEAAINDVYLAPLLQCLIEGLSAEPRVASNVCWAFSSLAEA
AYEAADVADDQEEPATYCLSSSFELIVQKLLETTDRPDGHQNNLRSSAYESLMEIVKNSA
KDCYPAVQKTTLVIMERLQQVLQMESHIQSTSDRIQFNDLQSLLCATLQNVLRKVQHQDA
LQISDVVMASLLRMFQSTAGSGGVQEDALMAVSTLVEVLGGEFLKYMEAFKPFLGIGLKN
YAEYQVCLAAVGLVGDLCRALQSNIIPFCDEVMQLLLENLGNENVHRSVKPQILSVFGDI
ALAIGGEFKKYLEVVLNTLQQASQAQVDKSDYDMVDYLNELRESCLEAYTGIVQGLKGDQ
ENVHPDVMLVQPRVEFILSFIDHIAGDEDHTDGVVACAAGLIGDLCTAFGKDVLKLVEAR
PMIHELLTEGRRSKTNKAKTLARWATKELRKLKNQA

Sequence of entity 2 (B), FASTA

>9N85_2 Ran-specific GTPase-activating protein (chains B)
HFQAVVPAPDEQEIATLEEDEEELFCNRAKLFRFASENDLPEWKERGTGDVKLLKHKEKG
AIRLLMRRDKTLKICANHYITPMMELKPNAGSDRAWVWNTHADFADECPKPELLAIRFLN
AENAQKFKTKFEECRKEIEEREKK

Sequence of entity 3 (C), FASTA

>9N85_3 GTP-binding nuclear protein Ran (chains C)
EPQVQFKLVLVGDGGTGKTTFVKRHLTGEFEKKYVATLGVEVHPLVFHTNRGPIKFNVWD
TAGQEKFGGLRDGYYIQAQCAIIMFDVTSRVTYKNVPNWHRDLVRVCENIPIVLCGNKVD
IKDRKVKAKSIVFHRKKNLQYYDISAKSNYNFEKPFLWLARKLIGDPNLEFVAMPALAPP
EVVMDPALAAQYEHDLEVAQTTALPEEDAA

Ligands and cofactors

ID	Name	Formula	Copies
MG	Magnesium ion	Mg	1
GTP	Guanosine-5'-triphosphate	C10 H16 N5 O14 P3	1

Primary citation

Ran modulates allosteric crosstalk between importin beta surfaces. Ko, Y.H., Li, F., Suinn, S.S. et al. Nat Commun (2025) 16:11425-11425. DOI 10.1038/s41467-025-66255-0 · PubMed

Other PDB entries of the same protein (UniProt Q14974 (AlphaFold model), which also has an AlphaFold model), best resolution first:

1IBR 2.3 Å, Complex of ran with importin beta
1QGR 2.3 Å, Structure of importin beta bound to the ibb domain of importin alpha (II crystal form,…
2P8Q 2.35 Å, Crystal Structure of human Importin beta bound to the Snurportin1 IBB-domain
1QGK 2.5 Å, Structure of importin beta bound to the ibb domain of importin alpha
3W5K 2.6 Å, Crystal structure of Snail1 and importin beta complex
1F59 2.8 Å, Importin-beta-fxfg nucleoporin complex
1O6O 2.8 Å, Importin Beta aa1-442 bound to five FxFG repeats from yeast Nsp1p. Second crystal form
1O6P 2.8 Å, Importin Beta bound to a GLFG Nucleoporin peptide
2QNA 2.84 Å, Crystal structure of human Importin-beta (127-876) in complex with the IBB-domain of…
1M5N 2.9 Å, Crystal structure of HEAT repeats (1-11) of importin b bound to the non-classical…
3LWW 3.15 Å, Structure of an open and closed conformation of Human Importin Beta bound to the…
2Q5D 3.2 Å, Crystal Structure of Human Importin Beta bound to the Snurportin1 IBB-domain second…

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