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Title
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Different length peptides bind to HLA-Aw68 similarly at their ends but bulge out in the middle.
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Authors
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H.C.Guo,
T.S.Jardetzky,
T.P.Garrett,
W.S.Lane,
J.L.Strominger,
D.C.Wiley.
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Ref.
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Nature, 1992,
360,
364-366.
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PubMed id
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Abstract
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We report here the determination and refinement to 1.9 A resolution by X-ray
cryo-crystallography the structure of HLA-Aw68. The averaged image from the
collection of bound, endogenous peptides clearly shows the atomic structure at
the first three and last two amino acids in the peptides but no connected
electron density in between. This suggests that bound peptides, held at both
ends, take alternative pathways and could be of different lengths by bulging out
in the middle. Peptides eluted from HLA-Aw68 include peptides of 9, 10 and 11
amino acids, a direct indication of the length heterogeneity of tightly bound
peptides. Peptide sequencing shows relatively conserved 'anchor' residues at
position 2 and the carboxy-terminal residue. Conserved binding sites for the
peptide N and C termini at the ends of the class I major histocompatibility
complex binding groove are apparently dominant in producing the long half-lives
of peptide binding and the peptide-dependent stabilization of the class I
molecule's structure.
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