9NX2: Muscle-type nicotinic acetylcholine receptor

Muscle-type nicotinic acetylcholine receptor bound to conotoxin ImII. Determined by electron microscopy at 2.96 Å resolution. Released 4 Feb 2026.

Method: Electron microscopy
Resolution: 2.96 Å
Organisms: Tetronarce californica, Conus imperialis
Chains: 7
Atoms: 17,103
Mol. weight: 275.85 kDa
Ligands: NAG, CCE
Released: 4 Feb 2026

Explore 9NX2 in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9NX2 contains 65 α-helices and 87 β-strands across 5 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: 13 helices, 13 β-strands

Element	Residues	Length	Sheet
α-helix	2-11	10
β-strand	29-44	16	1
β-strand	49-61	13	1
β-strand	77-81	5	1
α-helix	82-84	3
β-strand	91-92	2	2
β-strand	95	1	1
β-strand	107-111	5	1
β-strand	115-118	4	1
β-strand	121-127	7	1
β-strand	139-147	9	2
β-strand	156-160	5	1
β-strand	166	1	1
α-helix	170-172	3
β-strand	176-188	13	2
β-strand	198-209	12	2
α-helix	213-214	2
α-helix	215-219	5
α-helix	220-229	10
α-helix	230-233	4
α-helix	242-260	19
α-helix	273-299	27
α-helix	310-313	4
α-helix	314-319	6
α-helix	320-323	4
α-helix	370-418	49

Chain B: 13 helices, 19 β-strands

Element	Residues	Length	Sheet
α-helix	3-9	7
α-helix	10-14	5
β-strand	31-46	16	3
β-strand	51-63	13	3
β-strand	80-82	3	3
α-helix	84-86	3
β-strand	93-94	2	4
β-strand	97	1	3
β-strand	110-112	3	3
β-strand	117-120	4	3
β-strand	123-129	7	3
β-strand	141-149	9	4
β-strand	158-162	5	3
β-strand	164-166	3	5
β-strand	171-173	3	5
β-strand	176	1	6
β-strand	178-179	2	3
β-strand	185	1	3
β-strand	190-194	5	4
β-strand	196	1	6
β-strand	197-201	5	4
β-strand	213-223	11	4
α-helix	226-228	3
α-helix	229-233	5
α-helix	234-240	7
α-helix	241-248	8
α-helix	258-275	18
α-helix	287-313	27
α-helix	324-328	5
α-helix	329-333	5
α-helix	334-337	4
α-helix	419-473	55

Chain C: 12 helices, 21 β-strands

Element	Residues	Length	Sheet
α-helix	2-11	10
β-strand	29-44	16	7
β-strand	49-61	13	7
β-strand	77-80	4	7
α-helix	82-84	3
β-strand	90-92	3	8
β-strand	95	1	7
β-strand	104	1	7
β-strand	108-111	4	7
β-strand	115-118	4	7
β-strand	121-127	7	7
β-strand	139-148	10	8
β-strand	156-160	5	7
β-strand	162	1	9
β-strand	169	1	9
β-strand	172	1	10
β-strand	174-175	2	7
β-strand	181	1	7
β-strand	186-190	5	8
β-strand	192	1	10
β-strand	193-196	4	8
β-strand	206-215	10	8
α-helix	218-220	3
α-helix	221-225	5
α-helix	226-237	12
α-helix	238-240	3
α-helix	248-266	19
α-helix	279-305	27
β-strand	312	1	11
α-helix	316-319	4
α-helix	320-325	6
α-helix	326-330	5
α-helix	402-457	56

Chain D: 16 helices, 16 β-strands

Element	Residues	Length	Sheet
α-helix	2-11	10
β-strand	29-44	16	12
β-strand	49-61	13	12
α-helix	69-72	4
β-strand	77-78	2	12
β-strand	81	1	13
α-helix	82-84	3
β-strand	90-92	3	14
β-strand	95	1	12
β-strand	107	1	13
β-strand	109-111	3	12
β-strand	115-118	4	12
β-strand	121-127	7	12
β-strand	139-148	10	14
β-strand	156-160	5	12
β-strand	166	1	12
α-helix	170-173	4
β-strand	176-188	13	14
β-strand	198-209	12	14
α-helix	213-214	2
α-helix	215-219	5
α-helix	220-228	9
α-helix	229-234	6
α-helix	242-261	20
α-helix	273-299	27
α-helix	310-313	4
α-helix	314-319	6
α-helix	320-323	4
β-strand	329	1	11
α-helix	370-423	54
α-helix	426-428	3
α-helix	429-433	5

Chain E: 11 helices, 18 β-strands

Element	Residues	Length	Sheet
α-helix	3-11	9
β-strand	29-44	16	15
β-strand	49-61	13	15
α-helix	63-65	3
β-strand	77-80	4	15
β-strand	90-92	3	16
β-strand	95	1	15
β-strand	108-111	4	15
β-strand	115-118	4	15
β-strand	121-127	7	15
β-strand	139-148	10	16
β-strand	156-160	5	15
β-strand	162-163	2	17
β-strand	166-167	2	17
β-strand	170	1	18
β-strand	172	1	15
β-strand	184-188	5	16
β-strand	190	1	18
β-strand	191-195	5	16
β-strand	207-217	11	16
α-helix	220-222	3
α-helix	223-227	5
α-helix	228-234	7
α-helix	235-241	7
α-helix	252-270	19
α-helix	282-307	26
α-helix	319-325	7
α-helix	411-431	21
α-helix	435-469	35

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Acetylcholine receptor subunit alpha	A, D	protein	434	Tetronarce californica	P02710 (AlphaFold model)
Acetylcholine receptor subunit delta	B	protein	499	Tetronarce californica	P02718 (AlphaFold model)
Acetylcholine receptor subunit beta	C	protein	469	Tetronarce californica	P02712 (AlphaFold model)
Acetylcholine receptor subunit gamma	E	protein	489	Tetronarce californica	P02714 (AlphaFold model)
Alpha-conotoxin ImII	F, G	protein	13	Conus imperialis	Q8I6R5

Sequence of entity 1 (A, D), FASTA

>9NX2_1 Acetylcholine receptor subunit alpha (chains A, D)
SEHETRLVANLLENYNKVIRPVEHHTHFVDITVGLQLIQLISVDEVNQIVETNVRLRQQW
IDVRLRWNPADYGGIKKIRLPSDDVWLPDLVLYNNADGDFAIVHMTKLLLDYTGKIMWTP
PAIFKSYCEIIVTHFPFDQQNCTMKLGIWTYDGTKVSISPESDRPDLSTFMESGEWVMKD
YRGWKHWVYYTCCPDTPYLDITYHFIMQRIPLYFVVNVIIPCLLFSFLTGLVFYLPTDSG
EKMTLSISVLLSLTVFLLVIVELIPSTSSAVPLIGKYMLFTMIFVISSIIITVVVINTHH
RSPSTHTMPQWVRKIFIDTIPNVMFFSTMKRASKEKQENKIFADDIDISDISGKQVTGEV
IFQTPLIKNPDVKSAIEGVKYIAEHMKSDEESSNAAEEWKYVAMVIDHILLCVFMLICII
GTVSVFAGRKIELS

Sequence of entity 2 (B), FASTA

>9NX2_2 Acetylcholine receptor subunit delta (chains B)
NEEERLINDLLIVNKYNKHVRPVKHNNEVVNIALSLTLSNLISLKETDETLTSNVWMDHA
WYDHRLTWNASEYSDISILRLPPELVWIPDIVLQNNNDGQYHVAYFCNVLVRPNGYVTWL
PPAIFRSSCPINVLYFPFDWQNCSLKFTALNYDANEITMDLMTDTIDGKDYPIEWIIIDP
EAFTENGEWEIIHKPAKKNIYPDKFPNGTNYQDVTFYLIIRRKPLFYVINFITPCVLISF
LASLAFYLPAESGEKMSTAISVLLAQAVFLLLTSQRLPETALAVPLIGKYLMFIMSLVTG
VIVNCGIVLNFHFRTPSTHVLSTRVKQIFLEKLPRILHMSRADESEQPDWQNDLKLRRSS
SVGYISKAQEYFNIKSRSELMFEKQSERHGLVPRVTPRIGFGNNNENIAASDQLHDEIKS
GIDSTNYIVKQIKEKNAYDEEVGNWNLVGQTIDRLSMFIITPVMVLGTIFIFVMGNFNHP
PAKPFEGDPFDYSSDHPRC

Sequence of entity 3 (C), FASTA

>9NX2_3 Acetylcholine receptor subunit beta (chains C)
SVMEDTLLSVLFETYNPKVRPAQTVGDKVTVRVGLTLTNLLILNEKIEEMTTNVFLNLAW
TDYRLQWDPAAYEGIKDLRIPSSDVWQPDIVLMNNNDGSFEITLHVNVLVQHTGAVSWQP
SAIYRSSCTIKVMYFPFDWQNCTMVFKSYTYDTSEVTLQHALDAKGEREVKEIVINKDAF
TENGQWSIEHKPSRKNWRSDDPSYEDVTFYLIIQRKPLFYIVYTIIPCILISILAILVFY
LPPDAGEKMSLSISALLAVTVFLLLLADKVPETSLSVPIIIRYLMFIMILVAFSVILSVV
VLNLHHRSPNTHTMPNWIRQIFIETLPPFLWIQRPVTTPSPDSKPTIISRANDEYFIRKP
AGDFVCPVDNARVAVQPERLFSEMKWHLNGLTQPVTLPQDLKEAVEAIKYIAEQLESASE
FDDLKKDWQYVAMVADRLFLYVFFVICSIGTFSIFLDASHNVPPDNPFA

Sequence of entity 4 (E), FASTA

>9NX2_4 Acetylcholine receptor subunit gamma (chains E)
ENEEGRLIEKLLGDYDKRIIPAKTLDHIIDVTLKLTLTNLISLNEKEEALTTNVWIEIQW
NDYRLSWNTSEYEGIDLVRIPSELLWLPDVVLENNVDGQFEVAYYANVLVYNDGSMYWLP
PAIYRSTCPIAVTYFPFDWQNCSLVFRSQTYNAHEVNLQLSAEEGEAVEWIHIDPEDFTE
NGEWTIRHRPAKKNYNWQLTKDDTDFQEIIFFLIIQRKPLFYIINIIAPCVLISSLVVLV
YFLPAQAGGQKCTLSISVLLAQTIFLFLIAQKVPETSLNVPLIGKYLIFVMFVSMLIVMN
CVIVLNVSLRTPNTHSLSEKIKHLFLGFLPKYLGMQLEPSEETPEKPQPRRRSSFGIMIK
AEEYILKKPRSELMFEEQKDRHGLKRVNKMTSDIDIGTTVDLYKDLANFAPEIKSCVEAC
NFIAKSTKEQNDSGSENENWVLIGKVIDKACFWIALLLFSIGTLAIFLTGHFNQVPEFPF
PGDPRKYVP

Sequence of entity 5 (F, G), FASTA

>9NX2_5 Alpha-conotoxin ImII (chains F, G)
ACCSDRRCRWRCX

Ligands and cofactors

ID	Name	Formula	Copies
NAG	2-acetamido-2-deoxy-beta-D-glucopyranose	C8 H15 N O6	2
CCE	2-[(aminocarbonyl)oxy]-n,n,n-trimethylethanaminium	C6 H15 N2 O2	2

Primary citation

Shape-shifting conotoxins reveal divergent pore-targeting mechanisms in nicotinic receptors. Bhattacharjee, B., Noviello, C.M., Rahman, M.M. et al. Structure (2026) 34:463. DOI 10.1016/j.str.2025.12.003 · PubMed

Other PDB entries of the same protein (UniProt P02710 (AlphaFold model), which also has an AlphaFold model), best resolution first:

8YQN 2.27 Å, Torpedo acetylcholine receptor in complex with Erabutoxin A
7QL5 2.5 Å, Torpedo muscle-type nicotinic acetylcholine receptor - nicotine-bound conformation
7SMM 2.5 Å, Cryo-EM structure of Torpedo acetylcholine receptor in apo form
7SMT 2.56 Å, Cryo-EM structure of Torpedo acetylcholine receptor in complex with d-tubocurarine and…
6UWZ 2.69 Å, Cryo-EM structure of Torpedo acetylcholine receptor in complex with alpha-bungarotoxin
8F6Z 2.7 Å, Cryo-EM structure of Torpedo nicotinic acetylcholine receptor in complex with…
7SMQ 2.74 Å, Cryo-EM structure of Torpedo acetylcholine receptor in apo form with added cholesterol
7SMR 2.77 Å, Cryo-EM structure of Torpedo acetylcholine receptor in complex with carbachol,…
8F6Y 2.79 Å, Cryo-EM structure of Torpedo nicotinic acetylcholine receptor in complex with etomidate,…
9E3E 2.8 Å, Torpedo muscle-type nicotinic acetylcholine receptor - Diliganded State
7QKO 2.9 Å, Torpedo muscle-type nicotinic acetylcholine receptor - Resting conformation
8ESK 2.9 Å, Cryo-EM structure of Torpedo nicotinic acetylcholine receptor in complex with…

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