9E6G: Immunoglobulin heavy constant gamma 1

Locally Refined Cryo-EM map of 2G12 IgG BCR receptor lacking Fab region view. Determined by electron microscopy at 4.4 Å resolution. Released 24 Jun 2026.

Method: Electron microscopy
Resolution: 4.4 Å
Organism: Homo sapiens
Chains: 4
Atoms: 5,146
Mol. weight: 73.78 kDa
Ligands: NAG
Released: 24 Jun 2026

Explore 9E6G in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9E6G contains 15 α-helices and 58 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: 7 helices, 17 β-strands

Element	Residues	Length	Sheet
β-strand	25-29	5	1
α-helix	30-32	3
α-helix	33-37	5
β-strand	44-50	7	1
β-strand	60-65	6	2
β-strand	68-69	2	2
β-strand	74-76	3	1
β-strand	89-93	5	1
β-strand	105-110	6	2
β-strand	118-122	5	2
β-strand	133-137	5	3
α-helix	142-145	4
β-strand	148-158	11	3
β-strand	164-168	5	4
β-strand	173	1	4
β-strand	177-179	3	3
α-helix	180-182	3
β-strand	183	1	3
β-strand	190-199	10	3
α-helix	200-202	3
β-strand	210-214	5	4
α-helix	219-221	3
β-strand	223-226	4	4
α-helix	227-228	2

Chain B: 7 helices, 18 β-strands

Element	Residues	Length	Sheet
β-strand	25-29	5	5
α-helix	30-32	3
α-helix	33-35	3
β-strand	44-52	9	5
β-strand	60-65	6	6
β-strand	68-69	2	6
β-strand	74-75	2	5
β-strand	86-93	8	5
α-helix	96-99	4
β-strand	105-110	6	6
β-strand	118-122	5	6
β-strand	133-137	5	7
α-helix	143-145	3
β-strand	148-158	11	7
β-strand	164-169	6	8
β-strand	172-173	2	8
β-strand	177-179	3	7
β-strand	183-184	2	7
β-strand	190-199	10	7
α-helix	200-204	5
β-strand	208-214	7	8
α-helix	219-221	3
β-strand	223-228	6	8
α-helix	229-231	3
β-strand	232	1	9

Chain C: 0 helices, 11 β-strands

Element	Residues	Length	Sheet
β-strand	41-43	3	10
β-strand	50-52	3	11
β-strand	63-64	2	12
β-strand	65-69	5	13
β-strand	78-83	6	13
β-strand	91-93	3	11
β-strand	103-105	3	13
β-strand	107-109	3	12
β-strand	115-117	3	12
β-strand	121	1	13
β-strand	122-124	3	10

Chain D: 1 helix, 12 β-strands

Element	Residues	Length	Sheet
β-strand	47-48	2	14
β-strand	50	1	9
β-strand	52-53	2	15
β-strand	61	1	16
β-strand	64-66	3	14
β-strand	74-77	4	17
β-strand	97-100	4	14
β-strand	104-108	5	14
β-strand	109	1	16
α-helix	114-116	3
β-strand	119	1	15
β-strand	121-124	4	17
β-strand	139-140	2	15

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Immunoglobulin heavy constant gamma 1	A, B	protein	214	Homo sapiens	P01857 (AlphaFold model)
B-cell antigen receptor complex-associated protein alpha chain	C	protein	93	Homo sapiens	P11912 (AlphaFold model)
B-cell antigen receptor complex-associated protein beta chain	D	protein	100	Homo sapiens	P40259 (AlphaFold model)

Sequence of entity 1 (A, B), FASTA

>9E6G_1 Immunoglobulin heavy constant gamma 1 (chains A, B)
GGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQ
YNATYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIAATISKAKGQPREPQVYTLPPSR
EEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKS
RWQQGNVFSCSVMHEALHAHYTQKSLSLSPELQL

Sequence of entity 2 (C), FASTA

>9E6G_2 B-cell antigen receptor complex-associated protein alpha chain (chains C)
LWMHKVPASLMVSLGEDAHFQCPHNSSNNANVTWWRVLHGNYTWPPEFLGPGEDPNGTLI
IQNVNKSHGGIYVCRVQEGNESYQQSCGTYLRV

Sequence of entity 3 (D), FASTA

>9E6G_3 B-cell antigen receptor complex-associated protein beta chain (chains D)
ACSRIWQSPRFIARKRGFTVKMHCYMNSASGNVSWLWKQEMDENPQQLKLEKGRMEESQN
ESLATLTIQGIRFEDNGIYFCQQKCNNTSEVYQGCGTELR

Ligands and cofactors

ID	Name	Formula	Copies
NAG	2-acetamido-2-deoxy-beta-D-glucopyranose	C8 H15 N O6	5

Primary citation

Anti-HIV-1 B cell antigen receptor signaling and structure. Thakur, B., Acharya, P. To be published.

Other PDB entries of the same protein (UniProt P01857 (AlphaFold model), which also has an AlphaFold model), best resolution first:

4LLD 1.19 Å, Structure of wild-type IgG1 antibody heavy chain constant domain 1 and light chain…
3TV3 1.29 Å, Crystal structure of broad and potent HIV-1 neutralizing antibody PGT128 in complex with…
4LLQ 1.42 Å, Structure of redesigned IgG1 first constant and lambda domains (CH1:Clambda constant…
5HSF 1.52 Å, 1.52 Angstrom Crystal Structure of Fc fragment of Human IgG1.
6YT7 1.55 Å, Glycosylated knob/dummy-hole fc fragment
4NWU 1.6 Å, Crystal structure of APE1551, an anti-human NGF Fab with a nine amino acid insertion in…
1L6X 1.65 Å, Fc fragment of rituximab bound to a minimized version of the B-domain from protein A…
3TWC 1.65 Å, Crystal structure of broad and potent HIV-1 neutralizing antibody PGT127 in complex with…
5JIH 1.66 Å, Crystal structure of HER2 binding IgG1-Fc (Fcab STAB19)
3MCL 1.7 Å, Anti-beta-amyloid antibody c706 fab in space group P21
5U66 1.7 Å, Modified single helix from the B-domain of protein A bound to IgG1 Fc
6N35 1.75 Å, Anti-HIV-1 Fab 2G12 + Man1-2 re-refinement

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