The D96N mutation results in a loss of negative charge on the surface of the Mal-TIR domain in a region predicted to be involved in MyD88, but not TLR interactions. A, comparison of the electrostatic surfaces of wild-type (left) and Asn-96 (right) Mal-TIR models, indicating a loss of negative charge (red) in the region of residue 96 (circled). B, model of the TLR4-TIR homodimer (cyan)/Mal TIR domain (magenta) complex (20), indicating the location of Mal-D96 (red, space fill), its proximity to the predicted MyD88 interaction surface (pattern 108–122, yellow), and its distance from the BB-loop region (green) that is vital for the interaction of Mal with TLR4 (cyan).