A roadmap for HLA-A, HLA-B, and HLA-C peptide binding specificities.

The high level of polymorphism in major histocompatibility complex (MHC) molecules leads to many allele-specific peptide binding repertoires that can generally be characterized by sequence motifs. Such motifs have previously been elucidated experimentally for several MHC molecules and shown to bind in specificity pockets in the antigen binding cleft. Here, a new and less restrictive description of the traditional antigen binding pockets is derived. These regions are referred to as peptide binding environments and are defined as those residues in a fixed neighborhood of the peptide residues in known crystal structure complexes. By examining the antigen binding environments from MHC molecules with known motifs, we made predictions as to likely motifs for other MHC molecules which share the same environments. The predictions are presented in the form of Tables and are pertinent to class I HLA-A, HLA-B, and HLA-C MHC sequences, and are shown to correlate well with experiments.