We have previously found that a Tyr residue was critical for the interaction of peptides with the Kd molecule, and therefore may be acting as an anchor residue. In the present report we show that it is possible to convert a self peptide sequence into a Kd-restricted neo-antigen by a single Tyr substitution at position 2 of the peptide. This supports the idea that Tyr is a critical element in the binding motif of Kd-restricted peptides and is a finding that could also prove useful for vaccine development.