9S63: Echovirus 18 in situ, virion, I4

Name: PDB 9S63: Echovirus 18 in situ, virion, I4
Published: 2026-06-17
License: https://creativecommons.org/publicdomain/zero/1.0/
Keywords: virus

Echovirus 18 in situ, virion, I4. Determined by electron microscopy at 4.3 Å resolution. Released 17 Jun 2026.

Method: Electron microscopy
Resolution: 4.3 Å
Organism: Echovirus E18
Chains: 4
Atoms: 6,121
Mol. weight: 94.99 kDa
Released: 17 Jun 2026

Explore 9S63 in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9S63 contains 19 α-helices and 65 β-strands across 4 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: 9 helices, 22 β-strands

Element	Residues	Length	Sheet
β-strand	11	1	1
β-strand	14	1	2
α-helix	28-30	3
α-helix	32-34	3
α-helix	38-41	4
β-strand	44	1	2
β-strand	47	1	1
α-helix	54-56	3
β-strand	57	1	3
α-helix	58-62	5
β-strand	67	1	4
β-strand	72-75	4	4
α-helix	82-84	3
β-strand	86-87	2	5
α-helix	96-102	7
β-strand	105-108	4	6
β-strand	111-122	12	4
β-strand	136-142	7	5
β-strand	164-168	5	5
α-helix	172-174	3
β-strand	175-178	4	4
β-strand	187-188	2	6
β-strand	193	1	7
β-strand	194	1	8
β-strand	203	1	8
β-strand	213-218	6	5
β-strand	227-238	12	4
β-strand	242-245	4	6
α-helix	247-249	3
β-strand	260	1	9
β-strand	270	1	10

Chain B: 5 helices, 23 β-strands

Element	Residues	Length	Sheet
β-strand	14-15	2	11
β-strand	24-25	2	11
β-strand	32-33	2	12
α-helix	41-43	3
β-strand	54	1	13
β-strand	64-65	2	12
β-strand	69-70	2	14
β-strand	78-80	3	15
α-helix	82-85	4
α-helix	90-98	9
β-strand	101-103	3	13
β-strand	107-111	5	12
β-strand	119-127	9	15
β-strand	134	1	9
β-strand	153-154	2	15
β-strand	165	1	9
β-strand	171	1	16
β-strand	177	1	16
α-helix	178-183	6
β-strand	186-190	5	15
β-strand	196-200	5	12
β-strand	210	1	13
β-strand	215	1	7
β-strand	219-229	11	15
β-strand	239-240	2	14
β-strand	241-245	5	12
β-strand	250-252	3	13
α-helix	256-258	3

Chain C: 4 helices, 20 β-strands

Element	Residues	Length	Sheet
β-strand	23	1	4
α-helix	28-33	6
β-strand	39-40	2	6
β-strand	42	1	3
α-helix	43-48	6
β-strand	51-52	2	17
β-strand	58	1	10
β-strand	70-73	4	17
β-strand	85-87	3	18
α-helix	100-105	6
β-strand	108	1	19
β-strand	110-112	3	20
β-strand	115-121	7	17
β-strand	128	1	21
β-strand	129-136	8	18
α-helix	146-149	4
β-strand	154-159	6	18
β-strand	164-168	5	17
β-strand	178-179	2	20
β-strand	190-194	5	18
β-strand	200	1	21
β-strand	208-217	10	17
β-strand	222-223	2	20
β-strand	226	1	19

Chain D: 1 helix, 0 β-strands

Element	Residues	Length	Sheet
α-helix	51-54	4

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Genome polyprotein	A	protein	287	Echovirus E18	Q8V635 (AlphaFold model)
Echovirus 18 viral protein 2	B	protein	260	Echovirus E18	Q8V635 (AlphaFold model)
Echovirus 18 viral protein 3	C	protein	239	Echovirus E18	Q8V635 (AlphaFold model)
Echovirus 18 viral protein 4	D	protein	69	Echovirus E18	Q8V635 (AlphaFold model)

Sequence of entity 1 (A), FASTA

>9S63_1 Genome polyprotein (chains A)
GDNQDRTVANTQPSGPSNSTEIPALTAVETGHTSQVDPSDTIQTRHVVNFHSRSESTIEN
FMGRAACVFMDQYKINGEETSTDRFAVWTINIREMAQLRRKCEMFTYMRFDIEMTMVITS
CQDQGTILDQDMPVLTHQIMYVPPGGPIPAKVDGYEWQTSTNPSVFWTEGNAPPRISIPF
ISVGNAYSSFYDGWSHFTQDGTYGYTTLNAMGKLYIRHVNRSSPHQITSTIRVYFKPKHI
KAWVPRPPRLCPYINKRDVNFVVTEITDSRTSITDTPHPEHSVLATH

Sequence of entity 2 (B), FASTA

>9S63_2 Echovirus 18 viral protein 2 (chains B)
SPSAEECGYSDRVRSMTLGNSTITTQESANVVVGYGEWPSYLSDREATAEDQPTQPDVAT
CRFYTLESVQWEKTSPGWWWKFPEALKNMGLFGQNMHYHYLGRAGYTIHVQCNASKFHQG
CLLVVCVPEAEMGCADTDTTFPATELTTEDTPHVFTSDSITGKKVQAAVCNAGMGVGVGN
LTIFPHQWINLRTNNSATIVIPYINSVPMDNMFRHYNFTLMIIPFAPLNFTDGATAYVPI
TVTIAPMYAEYNGLRLASTQ

Sequence of entity 3 (C), FASTA

>9S63_3 Echovirus 18 viral protein 3 (chains C)
GVPVLNTPGSNQFLTSDDYQSPSAMPQFDETPEMHIPGEVRNLMEIAEVDSVVPVNNVTG
KTKSMDAYQIPVGTGNTDKTKPIFSFQMDPGYSSVLKRTLLGEMLNYYAHWSGSVKLTFL
FCGSAMATGKLLISYSPPGASVPTSRKDAMLGTHIVWDIGLQSSCVLCVPWISQSHYRMV
QQDPYTSAGYITCWYQTNIVVPPGAPTSCDVLCFASACNDFSVRLLRDTPFMAQPGKLQ

Sequence of entity 4 (D), FASTA

>9S63_4 Echovirus 18 viral protein 4 (chains D)
MGAQVSTQKTGAHETSLSAKGNSIIHYTNINFYKDAASSASNRQDIQQDPGKFTDPVKDL
MIKTLPALN

Primary citation

Particles of echovirus 18 open to release their genomes in vivo. Mukhamedova, L., Buchta, D., Trebichalska, Z. et al. Proc Natl Acad Sci U S A (2026) 123:e2601182123-e2601182123. DOI 10.1073/pnas.2601182123 · PubMed

Other PDB entries of the same protein (UniProt Q8V635 (AlphaFold model), which also has an AlphaFold model), best resolution first:

9TF0 2.26 Å, Structure of echovirus 18 in complex with neonatal Fc receptor
9TF1 2.44 Å, Structure of echovirus 18, activated particle
9TF2 2.86 Å, Structure of echovirus 18, empty particle
7B5F 2.9 Å, Structure of echovirus 18 in complex with neonatal Fc receptor
6HBG 3.16 Å, Echovirus 18 native particle
6HBJ 3.16 Å, Echovirus 18 empty particle
6HBH 3.36 Å, Echovirus 18 A-particle
6HBL 3.7 Å, Echovirus 18 Open particle without three pentamers
6HBK 3.8 Å, Echovirus 18 Open particle without one pentamer
6HHT 4.05 Å, Echovirus 18 Open particle without two pentamers
9SPU 6.5 Å, Echovirus 18 particle missing one pentamer in situ, symmetrized reconstruction (C5)

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