Figure 2:

Proton transport along hHv1. Outward transport (vignettes 1 to 12) involves the sequential binding to D174, E153, D112, D185, E119 and D123. Each proton transfer from one residue to the next involves conformational rearrangements that bring the two acidic residues closer together. The helices are shown in the same representation as in Figure 1. The acidic and basic residues and the conserved F150 are shown as sticks, oxygen atoms are shown in red, carbons in cyan, nitrogens in blue and hydrogens in white. The proton being transported is highlighted by a purple circle. Configurations in which the proton is bound to a protein residue are framed by a red box whereas configurations in which the proton is bound to a water molecule are framed in blue.