9CYM image
Entry Detail
PDB ID:
9CYM
Keywords:
Title:
Structure of LAG3 bound to the MHC class II molecule I-A(b)
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2024-08-02
Release Date:
2024-08-21
Method Details:
Experimental Method:
Resolution:
3.84 Å
R-Value Free:
0.30
R-Value Work:
0.25
R-Value Observed:
0.26
Space Group:
P 65 2 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:H-2 class II histocompatibility antigen, A-B alpha chain
Chain IDs:B (auth: A)
Chain Length:195
Number of Molecules:1
Biological Source:Mus musculus
Polymer Type:polypeptide(L)
Description:H-2 class II histocompatibility antigen, A beta chain
Chain IDs:D (auth: B)
Chain Length:191
Number of Molecules:1
Biological Source:Mus musculus
Polymer Type:polypeptide(L)
Description:Secreted lymphocyte activation gene 3 protein
Chain IDs:A (auth: L)
Chain Length:233
Number of Molecules:1
Biological Source:Mus musculus
Polymer Type:polypeptide(L)
Description:Class-II-associated invariant chain peptide
Chain IDs:C (auth: P)
Chain Length:16
Number of Molecules:1
Biological Source:Homo sapiens
Ligand Molecules
Primary Citation
Structural basis for mouse LAG3 interactions with the MHC class II molecule I-A b.
Nat Commun 15 7513 7513 (2024)
PMID: 39209860 DOI: 10.1038/s41467-024-51930-5

Abstact

The immune checkpoint protein, Lymphocyte activation gene-3 (LAG3), binds Major Histocompatibility Complex Class II (MHC-II) and suppresses T cell activation. Despite the recent FDA approval of a LAG3 inhibitor for the treatment of melanoma, how LAG3 engages MHC-II on the cell surface remains poorly understood. Here, we determine the 3.84 Å-resolution structure of mouse LAG3 bound to the MHC-II molecule I-Ab, revealing that domain 1 (D1) of LAG3 binds a conserved, membrane-proximal region of MHC-II spanning both the α2 and β2 subdomains. LAG3 dimerization restricts the intermolecular spacing of MHC-II molecules, which may attenuate T cell activation by enforcing suboptimal signaling geometry. The LAG3-MHC-II interface overlaps with the MHC-II-binding site of the T cell coreceptor CD4, implicating disruption of CD4-MHC-II interactions as a mechanism for LAG3 immunosuppressive function. Lastly, antibody epitope analysis indicates that multiple LAG3 inhibitors do not recognize the MHC-II-binding interface of LAG3, suggesting a role for functionally distinct mechanisms of LAG3 antagonism in therapeutic development.

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Primary Citation of related structures