9D72 | pdb_00009d72

CryoEM structure of anti-MHC-I Fab M1/42 complex with H2-Dd

• PDB DOI: https://doi.org/10.2210/pdb9D72/pdb
• EM Map EMD-46600: EMDB EMDataResource

• Classification: ANTITUMOR PROTEIN/Immune System
• Organism(s): Mus musculus, Rattus norvegicus, synthetic construct
• Expression System: Escherichia coli BL21(DE3), Homo sapiens
• Mutation(s): No 


• Deposited: 2024-08-16 Released: 2026-02-04 
• Deposition Author(s): Jiang, J., Natarajan, K., Margulies, D.H., Lei, H., Huang, R.
• Funding Organization(s): National Institutes of Health/National Institute Of Allergy and Infectious Diseases (NIH/NIAID)

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Experimental Data Snapshot

• Method: ELECTRON MICROSCOPY
• Resolution: 2.67 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

Starting Model: experimental

Literature

Structural mechanism of anti-MHC-I antibody blocking of inhibitory NK cell receptors in tumor immunity.

Jiang, J., Panda, A.K., Natarajan, K., Lei, H., Sharma, S., Boyd, L.F., Towler, R.R., Chempati, S., Ahmad, J., Morton, A.J., Lang, Z.C., Sun, Y., Sgourakis, N., Meier-Schellersheim, M., Huang, R.K., Shevach, E.M., Margulies, D.H.

(2026) Commun Biol 

• PubMed: 41629525 
• DOI: https://doi.org/10.1038/s42003-026-09641-8
• Primary Citation of Related Structures:  
  8TQ6, 9D72, 9D73, 9D74, 9OA9


• PubMed Abstract: 
  

  Anti-major histocompatibility complex class I (MHC-I) mAbs can stimulate immune responses to tumors and infections by blocking suppressive signals delivered via various immune inhibitory receptors. To understand such functions, we determined the structure of a highly cross-reactive anti-human MHC-I mAb, B1.23.2, in complex with the MHC-I molecule HLA-B*44:05 by both cryo-electron microscopy (cryo-EM) and X-ray crystallography. Structural models determined by the two methods were essentially identical revealing that B1.23.2 binds a conserved region on the α2 ₁ helix that overlaps the killer immunoglobulin-like receptor (KIR) binding site. Structural comparison to KIR/HLA complexes reveals a mechanism by which B1.23.2 blocks inhibitory receptor interactions, leading to natural killer (NK) cell activation. B1.23.2 treatment of the human KLM-1 pancreatic cancer model in humanized (NSG-IL15) mice provides evidence of suppression of tumor growth. Such anti-MHC-I mAb that block inhibitory KIR/HLA interactions may prove useful for tumor immunotherapy.

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Organizational Affiliation: 
• Molecular Biology Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA. [e-mail].
Cellular Immunology Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
Molecular Biology Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
Research Technology Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
Computational Systems Biology Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
Fred and Pamela Buffett Cancer Center and Eppley Institute for Cancer Research, Omaha, NE, USA.
Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA.
Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
Cellular Immunology Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA. [e-mail].
Molecular Biology Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA. [e-mail].

Biological Assembly 1  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Hetero 5-mer - A1B1C1D1E1 Pseudo Symmetry: Asymmetric - C1 
Pseudo Stoichiometry: Hetero 5-mer - A2B1C1D1 

Biological assembly 1 assigned by authors and generated by (software)

Biological Assembly Evidence: electron microscopy

Macromolecule Content 

• Total Structure Weight: 91.73 kDa 
• Atom Count: 6,040 
• Modeled Residue Count: 790 
• Deposited Residue Count: 816 
• Unique protein chains: 5

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Beta-2-microglobulin	A [auth B]	98	Mus musculus	Mutation(s): 0  Gene Names: B2m
UniProt & NIH Common Fund Data Resources
Find proteins for P01887 (Mus musculus) Explore P01887  Go to UniProtKB:  P01887
IMPC:  MGI:88127

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
Fab M1/42 Light Chain	B [auth L]	213	Rattus norvegicus	Mutation(s): 0

Entity ID: 3
Molecule	Chains	Sequence Length	Organism	Details	Image
Surface protein gp120	C [auth P]	10	synthetic construct	Mutation(s): 0
UniProt
Find proteins for P04582 (Human immunodeficiency virus type 1 group M subtype B (isolate BH8)) Explore P04582  Go to UniProtKB:  P04582

Entity ID: 4
Molecule	Chains	Sequence Length	Organism	Details	Image
H-2 class I histocompatibility antigen, D-D alpha chain	D [auth A]	273	Mus musculus	Mutation(s): 0  Gene Names: H2-D1
UniProt
Find proteins for P01900 (Mus musculus) Explore P01900  Go to UniProtKB:  P01900

Entity ID: 5
Molecule	Chains	Sequence Length	Organism	Details	Image
Fab M1/42 Heavy Chain	E [auth H]	222	Rattus norvegicus	Mutation(s): 0

Experimental Data & Validation

Experimental Data

• Method: ELECTRON MICROSCOPY
• Resolution: 2.67 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

EM Software:

Task	Software Package	Version
MODEL REFINEMENT	PHENIX	1.19.2-4158
RECONSTRUCTION	cryoSPARC	4.4.1

Structure Validation

Entry History & Funding Information

Deposition Data

• Released Date: 2026-02-04 
Deposition Author(s): Jiang, J., Natarajan, K., Margulies, D.H., Lei, H., Huang, R.

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Funding Organization	Location	Grant Number
National Institutes of Health/National Institute Of Allergy and Infectious Diseases (NIH/NIAID)	United States	Intramural

Revision History  

• Version 1.0: 2026-02-04
  Type: Initial release
  
• Version 1.1: 2026-02-11
  Changes: Data collection, Database references