An altered position of the alpha 2 helix of MHC class I is revealed by the crystal structure of HLA-B*3501.
Smith, K.J., Reid, S.W., Stuart, D.I., McMichael, A.J., Jones, E.Y., Bell, J.I.(1996) Immunity 4: 203-213
- PubMed: 8624811 
- DOI: https://doi.org/10.1016/s1074-7613(00)80429-x
- Primary Citation of Related Structures:  
1A1N - PubMed Abstract: 
The crystal structure of the human major histocompatibility complex class I B allele HLA B*3501 complexed with the 8-mer peptide epitope HIV1 Nef 75-82 (VPLRPMTY) has been determined at 2.0 angstrom resolution. Comparison with the crystal structure of the closely related allele HLA B*5301 reveals the structural basis for the tyrosine specificity of the B*3501 F pocket. The structure also reveals a novel conformation of the 8-mer peptide within the binding groove. The positions of the peptide N and C termini are nonstandard, but the classic pattern of hydrogen bonding to nonpolymorphic MHC class I residues is maintained, at the N terminus by addition of a water molecule, and at the C terminus by a substantial shift in the alpha 2 helix.
Organizational Affiliation: 
Nuffield Department of Clinical Medicine, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, United Kingdom.