3vj6

Structure of the MHC class Ib molecule Qa-1b

spinqualitylabelsall models 3vj6, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3vj6 is a 3 chain structure with sequence from Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.9Å Ligands: NI Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function HA15_MOUSE Involved in the presentation of foreign antigens to the immune system. Publication Abstract from PubMed 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 muM. Furthermore, we have determined the structure of Qa-1(b) bound to the leader sequence peptide, Qdm (AMAPRTLLL), to a resolution of 1.9 A 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. A structural basis for antigen presentation by the MHC class Ib molecule, Qa-1b.,Zeng L, Sullivan LC, Vivian JP, Walpole NG, Harpur CM, Rossjohn J, Clements CS, Brooks AG J Immunol. 2012 Jan 1;188(1):302-10. Epub 2011 Nov 30. PMID:22131332 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Beta-2 microglobulin 3D structures

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