9KWE: ICT01-BTN3A1/BTN3A2 complex

Cryo-EM structure of the ICT01-BTN3A1/BTN3A2 complex. Determined by electron microscopy at 3.7 Å resolution. Released 10 Dec 2025.

Method: Electron microscopy
Resolution: 3.7 Å
Organism: Homo sapiens
Chains: 4
Atoms: 6,557
Mol. weight: 150.9 kDa
Released: 10 Dec 2025

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

Secondary structure: helices and β-sheets

9KWE contains 12 α-helices and 90 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 E: 0 helices, 22 β-strands

Element	Residues	Length	Sheet
β-strand	33-34	2	1
β-strand	41	1	2
β-strand	51-54	4	1
β-strand	64-69	6	3
β-strand	75-80	6	3
β-strand	83-84	2	3
β-strand	99-100	2	1
β-strand	108-111	4	1
β-strand	122-129	8	3
β-strand	134-136	3	3
β-strand	139-141	3	3
β-strand	142	1	2
β-strand	145	1	4
β-strand	150-157	8	5
β-strand	162-168	7	5
β-strand	172	1	4
β-strand	176-180	5	6
β-strand	186-187	2	6
β-strand	189-191	3	5
β-strand	204-209	6	5
β-strand	219-223	5	6
β-strand	230-237	8	6

Chain F: 3 helices, 25 β-strands

Element	Residues	Length	Sheet
β-strand	32-34	3	7
β-strand	42-43	2	8
β-strand	48-49	2	9
β-strand	52	1	10
β-strand	53-55	3	7
β-strand	64-66	3	11
β-strand	69	1	11
β-strand	78	1	12
β-strand	85	1	12
α-helix	91-93	3
β-strand	98-103	6	9
α-helix	104-106	3
β-strand	108-113	6	9
α-helix	118-120	3
β-strand	122-129	8	11
β-strand	130	1	13
β-strand	133	1	13
β-strand	136-141	6	11
β-strand	143-144	2	8
β-strand	145	1	14
β-strand	150-154	5	6
β-strand	162-169	8	6
β-strand	172	1	14
β-strand	176-181	6	5
β-strand	190-196	7	6
β-strand	202-210	9	6
β-strand	217-223	7	5
β-strand	230-237	8	5

Chain H: 4 helices, 25 β-strands

Element	Residues	Length	Sheet
β-strand	3-6	4	15
β-strand	10-12	3	16
β-strand	17-25	9	15
β-strand	34-39	6	16
β-strand	45-51	7	16
α-helix	62-64	3
β-strand	70-71	2	15
β-strand	78-84	7	15
α-helix	88-90	3
β-strand	92-98	7	16
β-strand	99	1	17
β-strand	109	1	17
β-strand	116-120	5	16
α-helix	124-125	2
β-strand	126	1	18
β-strand	131-133	3	19
β-strand	145-150	6	19
β-strand	151-154	4	20
β-strand	155	1	18
β-strand	162-163	2	21
α-helix	164-166	3
β-strand	173-174	2	19
β-strand	185-187	3	20
β-strand	189-193	5	19
β-strand	204	1	22
β-strand	205-206	2	21
β-strand	207	1	23
β-strand	216	1	23
β-strand	219	1	22

Chain L: 5 helices, 18 β-strands

Element	Residues	Length	Sheet
β-strand	5-7	3	24
β-strand	19-24	6	24
β-strand	33-38	6	25
β-strand	45-49	5	25
β-strand	53-54	2	25
α-helix	55	1
β-strand	62-65	4	24
β-strand	70-75	6	24
β-strand	85-90	6	25
α-helix	96	1
β-strand	98	1	25
β-strand	114-118	5	26
α-helix	119-121	3
α-helix	122-126	5
β-strand	129-139	11	26
β-strand	144-150	7	27
β-strand	153-155	3	27
β-strand	161-164	4	26
α-helix	165-167	3
β-strand	173-182	10	26
β-strand	192-198	7	27
β-strand	205	1	27
β-strand	208-209	2	27

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Butyrophilin subfamily 3 member A2	E	protein	340	Homo sapiens	P78410 (AlphaFold model)
Butyrophilin subfamily 3 member A1	F	protein	539	Homo sapiens	O00481 (AlphaFold model)
ICT01 heavy chain	H	protein	254	Homo sapiens
ICT01 light chain	L	protein	236	Homo sapiens

Sequence of entity 1 (E), FASTA

>9KWE_1 Butyrophilin subfamily 3 member A2 (chains E)
MDMRVPAQLLGLLLLWLSGARCQFSVLGPSGPILAMVGEDADLPCHLFPTMSAETMELKW
VSSSLRQVVNVYADGKEVEDRQSAPYRGRTSILRDGITAGKAALRIHNVTASDSGKYLCY
FQDGDFYEKALVELKVAALGSNLHVEVKGYEDGGIHLECRSTGWYPQPQIQWSNAKGENI
PAVEAPVVADGVGLYEVAASVIMRGGSGEGVSCIIRNSLLGLEKTASISIADPFFRSAQP
WIAALAGTLPILLLLLAGASYFLWRQQKEITALSSEIESEQEMKEMGYAATEREISLRES
LQEELKRKKIQYLTRGEESSSDTNKSAGSSGMDYKDDDDK

Sequence of entity 2 (F), FASTA

>9KWE_2 Butyrophilin subfamily 3 member A1 (chains F)
MDMRVPAQLLGLLLLWLSGARCQFSVLGPSGPILAMVGEDADLPCHLFPTMSAETMELKW
VSSSLRQVVNVYADGKEVEDRQSAPYRGRTSILRDGITAGKAALRIHNVTASDSGKYLCY
FQDGDFYEKALVELKVAALGSDLHVDVKGYKDGGIHLECRSTGWYPQPQIQWSNNKGENI
PTVEAPVVADGVGLYAVAASVIMRGSSGEGVSCTIRSSLLGLEKTASISIADPFFRSAQR
WIAALAGTLPVLLLLLGGAGYFLWQQQEEKKTQFRKKKREQELREMAWSTMKQEQSTRVK
LLEELRWRSIQYASRGERHSAYNEWKKALFKPADVILDPKTANPILLVSEDQRSVQRAKE
PQDLPDNPERFNWHYCVLGCESFISGRHYWEVEVGDRKEWHIGVCSKNVQRKGWVKMTPE
NGFWTMGLTDGNKYRTLTEPRTNLKLPKPPKKVGVFLDYETGDISFYNAVDGSHIHTFLD
VSFSEALYPVFRILTLEPTALTICPAGSSGAWSHPQFEKGGGSGGGSGGSAWSHPQFEK

Sequence of entity 3 (H), FASTA

>9KWE_3 ICT01 heavy chain (chains H)
EFGLSWLFLVAILKGVQCQVQLVQSGAEVKKPGASVKLSCKASGYIFTRYYMYWVKQRPG
QGLEWIGEINPNNGGTKFNEKFKNRATLTVDKSISTAYMELSRLRSDDTAVYYCSREDDY
DGTPFAMDYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVS
WNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEP
KSCGGSHHHHHHHH

Sequence of entity 4 (L), FASTA

>9KWE_4 ICT01 light chain (chains L)
MDMRVPAQLLGLLLLWLSGARCDIQMTQSPSSLSASVGDRVTITCHASQNINVWLSWYQQ
KPGKAPKLLIYKASNLHTGVPSRFSGSGSGTDFTFTISSLQPEDIATYYCQQGQTYPYTF
GQGTKLEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGN
SQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC

Primary citation

Cryo-EM structure of the ICT01-BTN3A1/BTN3A2 complex at 3.7 Angstroms reolution. Xin, W.Z., Huang, B.D., Zhou, Q. To be published.

Other PDB entries of the same protein (UniProt P78410 (AlphaFold model), which also has an AlphaFold model), best resolution first:

4F8Q 2.38 Å, Crystal Structure of the Human BTN3A2 Ectodomain
8ZHR 3.0 Å, Cryo-EM structure of the full-length pAg-bound BTN2A1-BTN3A1-BTN3A2 complex
9JQR 3.0 Å, Cryo-EM structure of the Vgamma9Vdelta2 TCR-engaged BTN3A1-BTN3A2-BTN2A1 complex
9IRD 3.2 Å, Cryo-EM structure of BTN2A1-BTN3A1-BTN3A2 mutant (BTN3A1 H381R, BTN2A1 R477A/T510A) in…
9JQQ 3.26 Å, Cryo-EM structure of the HMBPP-primed BTN3A1-BTN3A2-BTN2A1 complex
9JQP 3.34 Å, Cryo-EM structure of the HMBPP-primed BTN3A1-BTN3A2-BTN2A1 in complex with agonist…
8ZJX 3.35 Å, Cryo-EM structure of the full length pAg-bound BTN2A1-BTN3A1-BTN3A2 in complex with…
8ZK0 3.4 Å, Cryo-EM structure of the full length pAg-bound BTN2A1-BTN3A1-BTN3A2 in complex with…
9L1P 3.5 Å, Cryo-EM structure of the ICT01-BTN2A1/BTN3A1/BTN3A2 complex, local refinement
9KWZ 3.7 Å, Cryo-EM structure of the ICT01-BTN2A1/BTN3A1/BTN3A2 complex
9L1O 3.7 Å, Cryo-EM structure of the ICT01-BTN3A1/BTN3A2 complex, local refinement
8ZK1 3.8 Å, Cryo-EM structure of BTN2A1-BTN3A1-BTN3A2 mutant complex (BTN3A1 H381R, BTN2A1…

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