12ER: BCMA

Cryo-EM structure of BCMA in complex with the BCMA-targeted Fab arm of teclistamab and the Fab fragment of an anti-lambda light chain antibody REGN15499. Determined by electron microscopy at 2.99 Å resolution. Released 12 Aug 2026.

Method: Electron microscopy
Resolution: 2.99 Å
Organisms: Mus musculus, Homo sapiens
Chains: 5
Atoms: 6,845
Mol. weight: 102.12 kDa
Released: 12 Aug 2026

Explore 12ER in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

12ER contains 27 α-helices and 93 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: 5 helices, 23 β-strands

Element	Residues	Length	Sheet
β-strand	3-7	5	1
β-strand	11-12	2	2
β-strand	17-25	9	1
α-helix	29-31	3
β-strand	34-39	6	3
β-strand	45-51	7	3
β-strand	58-59	2	3
β-strand	68-73	6	1
β-strand	78-84	7	1
α-helix	88-90	3
β-strand	92-98	7	3
β-strand	105	1	4
β-strand	106	1	3
β-strand	110-112	3	3
β-strand	113-114	2	2
α-helix	117-119	3
β-strand	120	1	5
β-strand	123-127	5	6
α-helix	128-130	3
β-strand	138-148	11	6
β-strand	149	1	5
β-strand	154-157	4	7
α-helix	158-160	3
β-strand	166-168	3	6
β-strand	172-174	3	6
β-strand	177-187	11	6
β-strand	197-202	6	7
β-strand	207-212	6	7

Chain B: 7 helices, 21 β-strands

Element	Residues	Length	Sheet
β-strand	4-7	4	8
β-strand	10-13	4	4
β-strand	19-25	7	8
β-strand	33-38	6	4
β-strand	44-49	6	4
β-strand	53-54	2	4
α-helix	55	1
β-strand	62-66	5	8
β-strand	70-75	6	8
α-helix	80-82	3
β-strand	85-90	6	4
α-helix	96	1
β-strand	97-98	2	4
β-strand	102-106	5	4
β-strand	111	1	9
β-strand	114-118	5	10
α-helix	119-121	3
α-helix	122-127	6
β-strand	129-139	11	10
β-strand	140	1	9
β-strand	144-150	7	11
β-strand	153-155	3	11
β-strand	159-163	5	10
β-strand	173-182	10	10
α-helix	183-187	5
β-strand	191-198	8	11
α-helix	204	1
β-strand	205-210	6	11

Chain C: 2 helices, 2 β-strands

Element	Residues	Length	Sheet
β-strand	12-15	4	12
β-strand	20-23	4	12
α-helix	24-28	5
α-helix	35-45	11

Chain D: 5 helices, 24 β-strands

Element	Residues	Length	Sheet
β-strand	3-7	5	13
β-strand	11-12	2	14
β-strand	17-25	9	13
β-strand	34	1	15
β-strand	36-41	6	15
β-strand	48-53	6	15
β-strand	60-61	2	15
α-helix	63-68	6
β-strand	69-74	6	13
β-strand	79-85	7	13
α-helix	89-91	3
β-strand	93-101	9	15
β-strand	107-111	5	15
β-strand	115-117	3	15
β-strand	118-119	2	14
α-helix	123-124	2
β-strand	125	1	16
β-strand	128-132	5	17
β-strand	143-153	11	17
β-strand	154	1	16
β-strand	159-162	4	18
β-strand	167	1	18
β-strand	172-173	2	17
α-helix	174-176	3
β-strand	177-178	2	17
β-strand	184-193	10	17
α-helix	194-196	3
β-strand	202-207	6	18
β-strand	214-219	6	18

Chain E: 8 helices, 23 β-strands

Element	Residues	Length	Sheet
β-strand	5	1	19
β-strand	9-12	4	20
β-strand	17-23	7	19
α-helix	27-29	3
β-strand	33-37	5	20
β-strand	44-47	4	20
β-strand	48	1	21
β-strand	52	1	21
β-strand	61-66	6	19
β-strand	69-75	7	19
α-helix	79-81	3
β-strand	84-91	8	20
β-strand	96-99	4	20
β-strand	103-107	5	20
α-helix	110-112	3
β-strand	113	1	22
β-strand	116-120	5	23
α-helix	121-123	3
α-helix	124-128	5
β-strand	132-141	10	23
β-strand	142	1	22
β-strand	147-151	5	24
β-strand	156-157	2	24
β-strand	161-163	3	23
α-helix	164-166	3
β-strand	167-168	2	23
β-strand	174-182	9	23
α-helix	184-188	5
β-strand	193-199	7	24
β-strand	202-208	7	24
α-helix	210-213	4

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Heavy chain of the Fab fragment of an anti-lambda light chain antibody REGN15499	A	protein	216	Mus musculus
Light chain of the Fab fragment of an anti-lambda light chain antibody REGN15499	B	protein	214	Mus musculus
Tumor necrosis factor receptor superfamily member 17	C	protein	82	Homo sapiens	Q02223 (AlphaFold model)
Heavy chain of the BCMA-targeted Fab arm of teclistamab	D	protein	221	Homo sapiens
Light chain of the BCMA-targeted Fab arm of teclistamab	E	protein	214	Homo sapiens

Sequence of entity 1 (A), FASTA

>12ER_1 Heavy chain of the Fab fragment of an anti-lambda light chain antibody REGN15499 (chains A)
EVQLVESGGGLVKPGGSLKLSCAASGFTFSAYAMSWVRQSPEKRLEWVADISSVGSHTYY
PDTVTGRFTISRDNAKNTLYLEMSSLRSEDTAMYYCARGDYNFDYWGQGTFLIVSSAKTT
APSVYPLAPVCGDTTGSSVTLGCLVKGYFPEPVTLTWNSGSLSSGVHTFPAVLQSDLYTL
SSSVTVTSSTWPSQSITCNVAHPASSTKVDKKIEPR

Sequence of entity 2 (B), FASTA

>12ER_2 Light chain of the Fab fragment of an anti-lambda light chain antibody REGN15499 (chains B)
DIQMTQSPSSLSASLGERVSLTCRASQEISGYLSWLQQKPDGTIKRLIYAASTLDSGVPK
RFSGSRSGSDYSLTISSLESEDFADYYCLQYANYPITFGAGTKLELKRADAAPTVSIFPP
SSEQLTSGGASVVCFLNNFYPKDINVKWKIDGSERQNGVLNSWTDQDSKDSTYSMSSTLT
LTKDEYERHNSYTCEATHKTSTSPIVKSFNRGEC

Sequence of entity 3 (C), FASTA

>12ER_3 Tumor necrosis factor receptor superfamily member 17 (chains C)
MLQMAGQCSQNEYFDSLLHACIPCQLRCSSNTPPLTCQRYCNASVTNSVKGTNAEQKLIS
EEDLGGEQKLISEEDLHHHHHH

Sequence of entity 4 (D), FASTA

>12ER_4 Heavy chain of the BCMA-targeted Fab arm of teclistamab (chains D)
QLQLQESGPGLVKPSETLSLTCTVSGGSISSGSYFWGWIRQPPGKGLEWIGSIYYSGITY
YNPSLKSRVTISVDTSKNQFSLKLSSVTAADTAVYYCARHDGAVAGLFDYWGQGTLVTVS
SASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQS
SGLYSLSSVVTVPSSSLGTKTYTCNVDHKPSNTKVDKRVES

Sequence of entity 5 (E), FASTA

>12ER_5 Light chain of the BCMA-targeted Fab arm of teclistamab (chains E)
SYVLTQPPSVSVAPGQTARITCGGNNIGSKSVHWYQQPPGQAPVVVVYDDSDRPSGIPER
FSGSNSGNTATLTISRVEAGDEAVYYCQVWDSSSDHVVFGGGTKLTVLGQPKAAPSVTLF
PPSSEELQANKATLVCLISDFYPGAVTVAWKGDSSPVKAGVETTTPSKQSNNKYAASSYL
SLTPEQWKSHRSYSCQVTHEGSTVEKTVAPTECS

Primary citation

DISTINCT EPITOPE ENGAGEMENT CONFERS DIFFERENTIAL ACTIVITY OF LINVOSELTAMAB VERSUS TECLISTAMAB ACROSS BCMA MUTATIONS. Zhou, Y., Sineshchekova, O., Lee, K. et al. Blood Adv (2026). DOI 10.1182/bloodadvances.2026020381 · PubMed

Other PDB entries of the same protein (UniProt Q02223 (AlphaFold model), which also has an AlphaFold model), best resolution first:

4ZFO 1.9 Å, J22.9-xi: chimeric mouse/human antibody against human BCMA (CD269)
1XU2 2.35 Å, The crystal structure of APRIL bound to BCMA
8HXQ 2.4 Å, Nanobody1 in complex with human BCMA ECD
1OQD 2.6 Å, Crystal structure of sTALL-1 and BCMA
6J7W 2.6 Å, Crystal Structure of Human BCMA in complex with UniAb(TM) VH
8HXR 2.7 Å, Nanobody2 in complex with human BCMA ECD
8QYA 2.72 Å, J22.9-FNY, fully humanized, CDR optimized Fab Fragment based on chimeric J22.9-xi IgG…
8QYB 3.09 Å, J22.9-ISY, fully humanized and CDR optimized Fab Fragment based on chimeric J22.9-xi IgG…
8QY9 3.1 Å, J22.9-H, fully humanized Fab Fragment based on chimeric J22.9-xi IgG against BCMA
9MQO 3.18 Å, Crystal structure of BCMA in complex with CA10v2 Fab
12ES 3.43 Å, Cryo-EM structure of BCMA in complex with the BCMA-targeted Fab arm of linvoseltamab and…
2KN1 Solution NMR Structure of BCMA

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