Consensus motifs and peptide ligands of MHC class I molecules.

The introduction of a powerful peptide isolation method has paved the way for the characterization of the natural peptide-ligands of MHC class I molecules. More than 50 are already known by their amino acid sequence. As a striking feature, all these peptides display some common sequence characteristics: a distinct peptide length, normally 8 or 9 amino acids, and typically two invariant 'anchor' amino acids. These 'consensus-motifs' are different for each MHC-class-I allele and their usefulness for the precise prediction of peptide antigens has already been demonstrated. This review discusses the consensus motifs known at present and lists most of the sequences referring to natural MHC-ligands.