Figure 1.

Electrostatic potential map of the P9 pocket. Electrostatic potential maps have been calculated separately for DR52a and DQ8 without their peptide and mapped to their van der Waals surface. The P9 pockets are shown here with their respective peptide P9 anchor side chain and selected residues in the pocket superimposed. The DR52a pocket is neutral and DQ8 shows a highly positive (blue) potential. The difference reflects the preference for a hydrophobic peptide side chain in DR52a P9 versus the preference for an acidic side chain in DQ8. The electrostatic difference is hypothesized to be a factor in susceptibility to T1D. Details of the calculations are given under supplementary materials (Additional file 1).