Send to

Choose Destination
Immunity. 1998 Mar;8(3):305-17.

Crystal structure of I-Ak in complex with a dominant epitope of lysozyme.

Author information

Howard Hughes Medical Institute, Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, USA.


We have determined the structure of murine MHC class II I-Ak in complex with a naturally processed peptide from hen egg lysozyme (HEL residues 50-62) at 1.9 A resolution. These results provide a structural basis for the I-Ak peptide-binding motif. Binding is established by the deep burial of five anchor side chains into specific pockets of the I-Ak binding groove, with a zen-like fit of an aspartic acid in the P1 pocket. We also show that in the I-Ak alpha chain, a bulge occurs in the first strand of the peptide-binding platform, an insertion probably common to all I-A and HLA-DQ alleles. The I-Ak beta chain has a deletion in the helical region adjacent to the P7 pocket and an insertion in the helical region neighboring the P1 pocket. As a result of these structural features, the extended HEL peptide dips low into the center of the I-Ak groove and reaches toward solvent at its C-terminal end.

[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center