PDBsum entry 4iiq

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protein ligands Protein-protein interface(s) links
Immune system PDB id
Protein chains
197 a.a.
243 a.a.
360 a.a.
SO4 ×3
Waters ×7
PDB id:
Name: Immune system
Title: Crystal structure of a human mait tcr in complex with bovine
Structure: Human mucosal associated invariant t cell recepto chain. Chain: a. Engineered: yes. Human mucosal associated invariant t cell recepto chain. Chain: b. Engineered: yes. Beta-2-microglobulin, mhc class i-related protein
Source: Homo sapiens. Human. Organism_taxid: 9606. Expressed in: escherichia coli. Expression_system_taxid: 562. Bos taurus. Bovine,cow,domestic cattle,domestic cow. Organism_taxid: 9913. Gene: mr1, bt.63045.
2.86Å     R-factor:   0.216     R-free:   0.271
Authors: J.Lopez-Sagaseta,E.J.Adams
Key ref: J.López-Sagaseta et al. (2013). The molecular basis for Mucosal-Associated Invariant T cell recognition of MR1 proteins. Proc Natl Acad Sci U S A, 110, E1771. PubMed id: 23613577 DOI: 10.1073/pnas.1222678110
20-Dec-12     Release date:   24-Apr-13    
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Protein chain
Pfam   ArchSchema ?
Q6P4G7  (Q6P4G7_HUMAN) -  TRA@ protein
260 a.a.
197 a.a.*
Protein chain
Pfam   ArchSchema ?
P01850  (TRBC1_HUMAN) -  T-cell receptor beta-1 chain C region
177 a.a.
243 a.a.*
Protein chain
No UniProt id for this chain
Struc: 360 a.a.
Key:    PfamA domain  Secondary structure  CATH domain
* PDB and UniProt seqs differ at 19 residue positions (black crosses)

 Gene Ontology (GO) functional annotation 
  GO annot!
  Cellular component     membrane   2 terms 
  Biological process     immune response   4 terms 
  Biochemical function     peptide antigen binding     1 term  


DOI no: 10.1073/pnas.1222678110 Proc Natl Acad Sci U S A 110:E1771 (2013)
PubMed id: 23613577  
The molecular basis for Mucosal-Associated Invariant T cell recognition of MR1 proteins.
J.López-Sagaseta, C.L.Dulberger, J.E.Crooks, C.D.Parks, A.M.Luoma, A.McFedries, I.Van Rhijn, A.Saghatelian, E.J.Adams.
Mucosal-associated invariant T (MAIT) cells are an evolutionarily conserved αβ T-cell lineage that express a semi-invariant T-cell receptor (TCR) restricted to the MHC related-1 (MR1) protein. MAIT cells are dependent upon MR1 expression and exposure to microbes for their development and stimulation, yet these cells can exhibit microbial-independent stimulation when responding to MR1 from different species. We have used this microbial-independent, cross-species reactivity of MAIT cells to define the molecular basis of MAIT-TCR/MR1 engagement and present here a 2.85 Å complex structure of a human MAIT-TCR bound to bovine MR1. The MR1 binding groove is similar in backbone structure to classical peptide-presenting MHC class I molecules (MHCp), yet is partially occluded by large aromatic residues that form cavities suitable for small ligand presentation. The docking of the MAIT-TCR on MR1 is perpendicular to the MR1 surface and straddles the MR1 α1 and α2 helices, similar to classical αβ TCR engagement of MHCp. However, the MAIT-TCR contacts are dominated by the α-chain, focused on the MR1 α2 helix. TCR β-chain contacts are mostly through the variable CDR3β loop that is positioned proximal to the CDR3α loop directly over the MR1 open groove. The elucidation of the MAIT TCR/MR1 complex structure explains how the semi-invariant MAIT-TCR engages the nonpolymorphic MR1 protein, and sheds light onto ligand discrimination by this cell type. Importantly, this structure also provides a critical link in our understanding of the evolution of αβ T-cell recognition of MHC and MHC-like ligands.