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[摘要]：Invariant Natural Killer T (iNKT) cells use highly restricted alpha beta Tcell receptors (TCRs) to probe the repertoire of lipids presented by CD1d molecules. Here, we describe our studies of lysophosphatidylcholine (LPC) presentation by human CD1d and its recognition by a native, LPC-specific iNKT TCR. Human CD1d presenting LPC adopts an altered conformation from that of CD1d presenting glycolipid antigens, with a shifted alpha 1 helix resulting in an open A' pocket. Binding of the iNKT TCR requires a 7-angstrom displacement of the LPC headgroup but stabilizes the CD1d-LPC complex in a closed conformation. The iNKT TCR CDR loop footprint on CD1d-LPC is anchored by the conserved positioning of the CDR3 alpha loop, whereas the remaining CDR loops are shifted, due in part to amino-acid differences in the CDR3 beta and J beta segment used by this iNKT TCR. These findings provide insight into how lysophospholipids are presented by human CD1d molecules and how this complex is recognized by some, but not all, human iNKT cells. The EMBO Journal (2012) 31, 2047-2059. doi:10.1038/emboj.2012.54; Published online 6 March 2012 Subject Categories: immunology |
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