Peptide motifs of closely related HLA class I molecules encompass substantial differences.
The peptides presented by major histocompatibility complex class I molecules adhere to strict rules concerning peptide length and occupancy by certain amino acid residues at anchor positions. Peptides presented by HLA-A*0201 molecules, for example, are generally nonapeptides requiring Leu or Met at position 2 and an aliphatic residue, predominantly Val, at position 9. A closely related molecule, HLA-A*0205, differing from the former at four amino acid residues, has a related but substantially different peptide motif. A*0205-presented peptides are still nonapeptides, and position 9 is still aliphatic, although it is preferentially occupied by Leu instead of Val. Position 2 not only allows aliphatic residues but also polar ones. Occupancy at position 6, considered as an auxiliary anchor in A*0201, as well as non-anchor residues at positions 3, 4, and 8 are relatively well conserved between the two peptide motifs. Thus, although a number of the T cell epitopes presented by the two HLA-A2 forms is expected to be identical, a considerable number of epitopes should be different.
Rötzschke
O
O
Max-Planck-Institut für Biologie, Abteilung Immunogenetik, Tübingen, FRG.
Falk
K
K
Stevanović
S
S
Jung
G
G
Rammensee
H G
HG
D000595:Amino Acid Sequence; D015234:HLA-A Antigens / Q000737:chemistry*; D006801:Humans; D008969:Molecular Sequence Data
D015234:HLA-A Antigens