1k2d: Difference between revisions

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'''Crystal structure of the autoimmune MHC class II I-Au complexed with myelin basic protein 1-11 at 2.2A'''

Murine experimental allergic encephalomyelitis (EAE) is a useful model for the demyelinating, autoimmune disease multiple sclerosis. In the EAE system, the immunodominant N-terminal epitope of myelin basic protein (MBP) is an unusually short, weakly binding peptide antigen which elicits highly biased TCR chain usage. In the 2.2 A crystal structure of I-A(u)/MBP1-11 complex, only MBP residues 1-7 are bound toward one end of the peptide binding cleft. The fourth residue of MBP1-11 is located in an incompatible p6 pocket of I-A(u), thus explaining the short half-life of I-A(u) complexed with Ac1-11. MBP peptides extended at the C terminus of Ac1-11 result in dramatic affinity increases, likely attributed to register shifting to a higher affinity cryptic epitope, which could potentially mask the presentation of the immunodominant MBP1-11 peptide during thymic education.

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