Figure 5.

Augmented, multi-state proton transport model, where at least three conformations take part in the conduction cycle. Protonation and deprotonation events are shown on the horizontal axis, while conformational changes are shown on the vertical axis. The first two protons bound can now be conducted by the “A” and “B” conformations, while the 3^rd proton is conducted by the “B” and “C” conformations. H⁺_o represent extraviral (N-terminal) protons, while H⁺_i represent intraviral (C-terminal protons). k₄, k₋₄, k₁₀, k₋₁₀ represent “leak” pathways.