9IQS: MT3-Muscarinic acetylcholine receptor 4

Cryo-EM structure of MT3-Muscarinic acetylcholine receptor 4. Determined by electron microscopy at 3.6 Å resolution. Released 23 Jul 2025.

Method: Electron microscopy
Resolution: 3.6 Å
Organisms: Dendroaspis angusticeps, Homo sapiens, synthetic construct
Chains: 2
Atoms: 2,738
Mol. weight: 56.17 kDa
Released: 23 Jul 2025

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

Secondary structure: helices and β-sheets

9IQS contains 15 α-helices and 5 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.

Chain A: 0 helices, 5 β-strands

Element	Residues	Length	Sheet
β-strand	3-4	2	1
β-strand	14-15	2	1
β-strand	24-32	9	2
β-strand	35-42	8	2
β-strand	54-58	5	2

Chain B: 15 helices, 0 β-strands

Element	Residues	Length
α-helix	29-60	32
α-helix	66-80	15
α-helix	81-86	6
α-helix	87-93	7
α-helix	104-135	32
α-helix	141-144	4
α-helix	147-175	29
α-helix	189-191	3
α-helix	193-200	8
α-helix	201-205	5
α-helix	206-225	20
α-helix	392-422	31
α-helix	433-441	9
α-helix	444-456	13
α-helix	458-468	11

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Muscarinic toxin 3	A	protein	65	Dendroaspis angusticeps	P81031 (AlphaFold model)
Muscarinic acetylcholine receptor M4,Soluble cytochrome b562	B	protein	432	Homo sapiens, synthetic construct	P08173 (AlphaFold model)

Sequence of entity 1 (A), FASTA

>9IQS_1 Muscarinic toxin 3 (chains A)
LTCVTKNTIFGITTENCPAGQNLCFKRWHYVIPRYTEITRGCAATCPIPENYDSIHCCKT
DKCNE

Sequence of entity 2 (B), FASTA

>9IQS_2 Muscarinic acetylcholine receptor M4,Soluble cytochrome b562 (chains B)
HNRYETVEMVFIATVTGSLSLVTVVGNILVMLSIKVNRQLQTVNNYFLFSLACADLIIGA
FSMNLYTVYIIKGYWPLGAVVCDLWLALDYVVSNASVMNLLIISFDRYFCVTKPLTYPAR
RTTKMAGLMIAAAWVLSFVLWAPAILFWQFVVGKRTVPDNQCFIQFLSNPAVTFGTAIAA
FYLPVVIMTVLYIHISLASRSRVADLEDNWETLNDNLKVIEKADNAAQVKDALTKMRAAA
LDAQKASGSGSPEMKDFRHGFDILVGQIDDALKLANEGKVKEAQAAAEQLKTTRNAYIQK
YLRMAARERKVTRTIFAILLAFILTWTPYNVMVLVNTFCQSCIPDTVWSIGYWLCYVNST
INPACYALCNATFKKTFRHLLLKIAALKEKIAALKEKIAALKEAEEKRASRLEEELRRRL
TEGSHHHHHHHH

Primary citation

Structure-guided engineering of snake toxins for selective modulation of adrenergic and muscarinic receptors. Zhong, Y., Tao, H., Zhang, Y. et al. Nat Commun (2025) 16:6478-6478. DOI 10.1038/s41467-025-61695-0 · PubMed

Other PDB entries of the same protein (UniProt P81031 (AlphaFold model), which also has an AlphaFold model), best resolution first:

9IQV 3.3 Å, Cryo-EM structure of MT3-alpha1AAR
9IQR 3.4 Å, Cryo-EM structure of MT3-alpha2AAR

Browse structure collections

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