9E4D: Acid-sensing ion channel 1

Human ASIC1a at pH 7.5 with linear transmembrane domain. Determined by electron microscopy at 3.19 Å resolution. Released 21 Jan 2026.

Method: Electron microscopy
Resolution: 3.19 Å
Organism: Homo sapiens
Chains: 3
Atoms: 9,915
Mol. weight: 180.76 kDa
Released: 21 Jan 2026

Explore 9E4D in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9E4D contains 81 α-helices and 72 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: 28 helices, 24 β-strands

Element	Residues	Length	Sheet
α-helix	41-69	29
β-strand	73-80	8	1
β-strand	85-86	2	2
α-helix	87-88	2
β-strand	89-94	6	3
β-strand	99	1	4
α-helix	105-111	7
α-helix	132-142	11
α-helix	154-161	8
α-helix	163-164	2
α-helix	165-168	4
β-strand	171-174	4	5
β-strand	177-178	2	5
α-helix	181-183	3
β-strand	184-189	6	3
β-strand	192-197	6	3
α-helix	200-202	3
α-helix	204-207	4
β-strand	208-209	2	2
α-helix	214-216	3
β-strand	218-223	6	5
α-helix	226-228	3
β-strand	229	1	4
α-helix	230-232	3
β-strand	243	1	6
β-strand	245-250	6	3
β-strand	263-265	3	3
β-strand	269-275	7	5
β-strand	276-281	6	1
α-helix	283-284	2
α-helix	290	1
β-strand	291	1	7
α-helix	292	1
α-helix	293-296	4
α-helix	307-323	17
β-strand	326	1	8
α-helix	335	1
β-strand	336	1	8
α-helix	337-338	2
α-helix	339-341	3
α-helix	342-346	5
α-helix	347-351	5
α-helix	352-356	5
α-helix	363-365	3
β-strand	366	1	7
β-strand	368-373	6	1
β-strand	376-380	5	5
α-helix	387-393	7
α-helix	398-404	7
β-strand	405-412	8	5
β-strand	417-424	8	1
α-helix	428-451	24

Chain B: 27 helices, 24 β-strands

Element	Residues	Length	Sheet
α-helix	41-70	30
β-strand	73-80	8	9
β-strand	85-86	2	10
α-helix	87-88	2
β-strand	89-94	6	11
β-strand	99	1	12
α-helix	105-111	7
α-helix	127-129	3
α-helix	132-141	10
α-helix	154-161	8
α-helix	163-164	2
α-helix	165-168	4
β-strand	169-174	6	6
β-strand	177	1	6
α-helix	181-183	3
β-strand	184-189	6	11
β-strand	192-197	6	11
α-helix	200-202	3
α-helix	204-207	4
β-strand	208-209	2	10
β-strand	218-223	6	6
α-helix	226-228	3
β-strand	229	1	12
α-helix	230-232	3
β-strand	243	1	13
β-strand	245-250	6	11
α-helix	255-256	2
α-helix	258-261	4
β-strand	263-265	3	11
β-strand	269-275	7	6
β-strand	276-281	6	9
β-strand	291	1	14
α-helix	293-296	4
α-helix	307-323	17
β-strand	326	1	15
α-helix	335	1
β-strand	336	1	15
α-helix	337-338	2
α-helix	339-341	3
α-helix	342-346	5
α-helix	347-351	5
α-helix	352-356	5
α-helix	364-365	2
β-strand	366	1	14
β-strand	368-373	6	9
β-strand	376-380	5	6
α-helix	387-393	7
α-helix	398-404	7
β-strand	405-412	8	6
β-strand	417-424	8	9
α-helix	428-451	24

Chain C: 26 helices, 24 β-strands

Element	Residues	Length	Sheet
α-helix	41-69	29
β-strand	73-80	8	16
β-strand	85-86	2	17
α-helix	87-88	2
β-strand	89-94	6	18
β-strand	99	1	19
α-helix	105-111	7
α-helix	127-129	3
α-helix	132-141	10
α-helix	154-161	8
α-helix	163-164	2
α-helix	165-168	4
β-strand	169-174	6	13
β-strand	177	1	13
α-helix	181-183	3
β-strand	184-189	6	18
β-strand	192-197	6	18
α-helix	200-202	3
α-helix	204-207	4
β-strand	208-209	2	17
β-strand	218-223	6	13
α-helix	226-228	3
β-strand	229	1	19
α-helix	230-232	3
β-strand	243	1	5
β-strand	245-250	6	18
α-helix	255-256	2
α-helix	258-261	4
β-strand	263-265	3	18
β-strand	269-275	7	13
β-strand	276-281	6	16
β-strand	291	1	20
α-helix	307-323	17
β-strand	326	1	21
α-helix	335	1
β-strand	336	1	21
α-helix	337-338	2
α-helix	339-341	3
α-helix	342-346	5
α-helix	347-351	5
α-helix	352-356	5
α-helix	364-365	2
β-strand	366	1	20
β-strand	368-373	6	16
β-strand	376-380	5	13
α-helix	387-393	7
α-helix	398-402	5
β-strand	405-412	8	13
β-strand	417-424	8	16
α-helix	428-451	24

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Acid-sensing ion channel 1	A, B, C	protein	531	Homo sapiens	P78348 (AlphaFold model)

Sequence of entity 1 (A, B, C), FASTA

>9E4D_1 Acid-sensing ion channel 1 (chains A, B, C)
GGRMELKAEEEEVGGVQPVSIQAFASSSTLHGLAHIFSYERLSLKRALWALCFLGSLAVL
LCVCTERVQYYFHYHHVTKLDEVAASQLTFPAVTLCNLNEFRFSQVSKNDLYHAGELLAL
LNNRYEIPDTQMADEKQLEILQDKANFRSFKPKPFNMREFYDRAGHDIRDMLLSCHFRGE
VCSAEDFKVVFTRYGKCYTFNSGRDGRPRLKTMKGGTGNGLEIMLDIQQDEYLPVWGETD
ETSFEAGIKVQIHSQDEPPFIDQLGFGVAPGFQTFVACQEQRLIYLPPPWGTCKAVTMDS
DLDFFDSYSITACRIDCETRYLVENCNCRMVHMPGDAPYCTPEQYKECADPALDFLVEKD
QEYCVCEMPCNLTRYGKELSMVKIPSKASAKYLAKKFNKSEQYIGENILVLDIFFEVLNY
ETIEQKKAYEIAGLLGDIGGQMGLFIGASILTVLELFDYAYEVIKHKLCRRGKCQKEAKR
SSADKGVALSLDDVKRHNPCESLRGHPAGMTYAANILPHHPARGTFEDFTC

Primary citation

Conformational plasticity of human acid-sensing ion channel 1a. Cahill, J., Hartfield, K.A., Heusser, S.A. et al. Nat Struct Mol Biol (2026) 33:1171-1182. DOI 10.1038/s41594-026-01845-0 · PubMed

Other PDB entries of the same protein (UniProt P78348 (AlphaFold model), which also has an AlphaFold model), best resolution first:

9E4I 2.33 Å, Human ASIC1a at pH 7.5 in complex with MitTx
9E4H 2.61 Å, Human ASIC1a at pH 5.7 with rotated, domain-swapped transmembrane domain
9E4F 2.69 Å, Human ASIC1a at pH 5.7 with domain-swapped transmembrane domain
9E4A 2.74 Å, Human ASIC1a at pH 8.5 with domain-swapped transmembrane domain
9E4K 2.77 Å, Human ASIC1a at pH 8.5, T26V mutation
9E4G 2.8 Å, Human ASIC1a at pH 5.7 with linear transmembrane domain
6L6N 2.86 Å, hASIC1a co-crystallized with Nafamostat
7RNN 2.86 Å, Human ASIC1a-Nb.C1 complex
9E4J 2.87 Å, Human ASIC1a at pH 6.5 in complex with MitTx
9E4B 3.09 Å, Human ASIC1a at pH 7.5 with domain-swapped transmembrane domain
9E4E 3.16 Å, Human ASIC1a at pH 6.5 with linear transmembrane domain
6L6I 3.24 Å, hASIC1a co-crystallized with Mamb-1

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