Dissection of major histocompatibility complex (MHC) and T cell receptor contact residues in a K^b‐restricted ovalbumin peptide and an assessment of the predictive power of MHC‐binding motifs

The effect of alanine substitution on the major histocompatibility complex (MHC) binding and T cell receptor recognition of the K^b‐restricted ovalbumin 257–264 peptide was investigated. Positions 3, 5 and 8 of the octamer were important for K^b binding, as predicted from the motifs found in K^b‐associated peptides, while mutations at positions 4, 6 and 7 affected cytotoxic T lymphocyte recognition. Substitutions at positions 1 and 2 had very minor effects on T cell recognition. In addition, we tested the capacity of sequence motifs to predict MHC binding by analysis of a series of peptides which all bear the minimal K^b motif. We found that possession of good motifs was not always sufficient to give strong MHC binding, indicating secondary effects of the residues flanking the „MHC anchor” positions.