3rzc
From Proteopedia
Structure of the self-antigen iGb3 bound to mouse CD1d and in complex with the iNKT TCR
Structural highlights
Function[CD1D1_MOUSE] Antigen-presenting protein that binds self and non-self glycolipids and presents them to T-cell receptors on natural killer T-cells.[1] [2] [3] [B2MG_MOUSE] Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system. Publication Abstract from PubMedInvariant NKT (iNKT) cells expressing a semi-invariant Valpha14 TCR recognize self and foreign lipid Ags when presented by the nonclassical MHCI homolog CD1d. Whereas the majority of known iNKT cell Ags are characterized by the presence of a single alpha-linked sugar, mammalian self Ags are beta-linked glycosphingolipids, posing the interesting question of how the semi-invariant TCR can bind to such structurally distinct ligands. In this study, we show that the mouse iNKT TCR recognizes the complex beta-linked Ag isoglobotrihexosylceramide (iGb3; Galalpha1-3-Galbeta1-4-Glcbeta1-1Cer) by forcing the proximal beta-linked sugar of the trisaccharide head group to adopt the typical binding orientation of alpha-linked glycolipids. The squashed iGb3 orientation is stabilized by several interactions between the trisaccharide and CD1d residues. Finally, the formation of novel contacts between the proximal and second sugar of iGb3 and CDR2alpha residues of the TCR suggests an expanded recognition logic that can possibly distinguish foreign Ags from self Ags. Cutting Edge: Structural Basis for the Recognition of {beta}-Linked Glycolipid Antigens by Invariant NKT Cells.,Yu ED, Girardi E, Wang J, Zajonc DM J Immunol. 2011 Sep 1;187(5):2079-83. Epub 2011 Aug 1. PMID:21810611[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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