Potential interactions of D455 and F455 with TM1 and with membrane lipids. (A) Side view of the predicted WT hASIC1a and mutant F455 in the resting (upper panel) and open (lower panel) conformations highlighting interactions formed by residues D/F455. Only two subunits at the membrane level are shown. (B) Above structures shown on surface representation. The side chains of residues D455 and F455 are in contact with the membrane lipids shown by the exposed surface colored in cyan.