T cell receptor view of the α1β1 domain of DQA1*0301/B1*0302 (DQ8) complexed with the α-I gliadin peptide, identified as a DQ8-specific epitope (Table 1). Color conventions and representations are as in Figure 1. DQ8 is also unique in its preference for acidic residues at p1 and p9 (40−43). These anchors also point into the plane of the paper and are not visible to the viewer. Four arginines around p1 (α49, α50, α52 [not shown], and α53) are responsible for the preference of an acidic residue at p1, and α76Arg is responsible for a similar preference at p9. The peptide shown here is the transformed gliadin peptide (p1/9Glu), which is recognized by the same T cell clone, but at a higher sensitivity than the native one (p1/9Gln) (1, 6, 9, 43).