Interior pH-sensing residue of human voltage-gated proton channel H1 is histidine 168.

The molecular mechanisms governing the human voltage-gated proton channel hH1 remain elusive. Here, we used membrane-enabled hybrid-solvent continuous constant pH molecular dynamics (CpHMD) simulations with pH replica exchange to further evaluate the structural models of hH1 in the closed (hyperpolarized) and open (depolarized) states recently obtained with MD simulations and explore potential pH-sensing residues. The CpHMD titration at a set of symmetric pH conditions revealed three residues that can gain or lose protons upon channel depolarization.

Interaction with stomatin directs human proton channels into cholesterol-dependent membrane domains.

Many membrane proteins are modulated by cholesterol. Here we report profound effects of cholesterol depletion and restoration on the human voltage-gated proton channel, hH1, in excised patches but negligible effects in the whole-cell configuration. Despite the presence of a putative cholesterol-binding site, a CARC motif in hH1, mutation of this motif did not affect cholesterol effects.

Unexpected expansion of the voltage-gated proton channel family.

Voltage-gated ion channels, whose first identified function was to generate action potentials, are divided into subfamilies with numerous members. The family of voltage-gated proton channels (H ) is tiny. To date, all species found to express H have exclusively one gene that codes for this unique ion channel.

Analysis of an electrostatic mechanism for ΔpH dependent gating of the voltage-gated proton channel, H1, supports a contribution of protons to gating charge.

Voltage-gated proton channels (H1) resemble the voltage-sensing domain of other voltage-gated ion channels, but differ in containing the conduction pathway. Essential to the functions of H1 channels in many cells and species is a unique feature called ΔpH dependent gating. The pH on both sides of the membrane strictly regulates the voltage range of channel opening, generally resulting in exclusively outward proton current.

Engineered high-affinity zinc binding site reveals gating configurations of a human proton channel.

The voltage-gated proton channel (HV1) is a voltage sensor that also conducts protons. The singular ability of protons to penetrate proteins complicates distinguishing closed and open channels. When we replaced valine with histidine at position 116 in the external vestibule of hHV1, current was potently inhibited by externally applied Zn2+ in a construct lacking the two His that bind Zn2+ in WT channels.