3VJ6

Structure of the MHC class Ib molecule Qa-1b

Summary for 3VJ6

• Entry DOI: 10.2210/pdb3vj6/pdb
• Descriptor: H-2 class I histocompatibility antigen, D-37 alpha chain, Beta-2-microglobulin, Qdm peptide, ... (5 entities in total)
• Functional Keywords: mhc-classib, immunoglobulin fold, immune system, peptide presentation, cd94-nkg2a/c receptors
• Biological source: Mus musculus (mouse); More
• Cellular location: Membrane; Single-pass type I membrane protein: P06339 P01897; Secreted: P01887
• Total number of polymer chains: 3
• Total formula weight: 45403.39

Authors

Zeng, L.,Clements, C.S.,Rossjohn, J. (deposition date: 2011-10-12, release date: 2012-03-14, Last modification date: 2024-10-30)

Primary citation

Zeng, L.,Sullivan, L.C.,Vivian, J.P.,Walpole, N.G.,Harpur, C.M.,Rossjohn, J.,Clements, C.S.,Brooks, A.G.
A structural basis for antigen presentation by the MHC class Ib molecule, Qa-1b
J.Immunol., 188:302-310, 2012

PubMed Abstract: The primary function of the monomorphic MHC class Ib molecule Qa-1(b) is to present peptides derived from the leader sequences of other MHC class I molecules for recognition by the CD94-NKG2 receptors expressed by NK and T cells. Whereas the mode of peptide presentation by its ortholog HLA-E, and subsequent recognition by CD94-NKG2A, is known, the molecular basis of Qa-1(b) function is unclear. We have assessed the interaction between Qa-1(b) and CD94-NKG2A and shown that they interact with an affinity of 17 μM. Furthermore, we have determined the structure of Qa-1(b) bound to the leader sequence peptide, Qdm (AMAPRTLLL), to a resolution of 1.9 Å and compared it with that of HLA-E. The crystal structure provided a basis for understanding the restricted peptide repertoire of Qa-1(b). Whereas the Qa-1(b-AMAPRTLLL) complex was similar to that of HLA-E, significant sequence and structural differences were observed between the respective Ag-binding clefts. However, the conformation of the Qdm peptide bound by Qa-1(b) was very similar to that of peptide bound to HLA-E. Although a number of conserved innate receptors can recognize heterologous ligands from other species, the structural differences between Qa-1(b) and HLA-E manifested in CD94-NKG2A ligand recognition being species specific despite similarities in peptide sequence and conformation. Collectively, our data illustrate the structural homology between Qa-1(b) and HLA-E and provide a structural basis for understanding peptide repertoire selection and the specificity of the interaction of Qa-1(b) with CD94-NKG2 receptors.

PubMed: 22131332
DOI: 10.4049/jimmunol.1102379

Experimental method

X-RAY DIFFRACTION (1.9 Å)