Gating Charge Displacement In A Monomeric Voltage-Gated Proton (H(V)1) Channel

Significance H v 1 proton channels, since their open probability increases with depolarization and low pH, are fundamental in sustaining the suitable pH gradient for cell survival. Here, we have characterized the gating current elicited by the monomeric mutant proton channel N264R with the aim of understanding the voltage-dependent processes that control channel opening. Gating currents precede ion currents, indicating that a large fraction of gating charge is displaced before H v 1 opening. The voltage sensor displacements are complex and consist of numerous well-defined states. However, most of the charge is displaced in a single transition that probably leads to channel opening. The positively charged arginine in the N264R channel promotes gating charge trapping in addition to blocking the proton currents.