A voltage-gated proton-selective channel lacking the pore domain

Nature. 2006 Apr 27;440(7088):1213-6. doi: 10.1038/nature04700. Epub 2006 Mar 22.

Abstract

Voltage changes across the cell membrane control the gating of many cation-selective ion channels. Conserved from bacteria to humans, the voltage-gated-ligand superfamily of ion channels are encoded as polypeptide chains of six transmembrane-spanning segments (S1-S6). S1-S4 functions as a self-contained voltage-sensing domain (VSD), in essence a positively charged lever that moves in response to voltage changes. The VSD 'ligand' transmits force via a linker to the S5-S6 pore domain 'receptor', thereby opening or closing the channel. The ascidian VSD protein Ci-VSP gates a phosphatase activity rather than a channel pore, indicating that VSDs function independently of ion channels. Here we describe a mammalian VSD protein (H(V)1) that lacks a discernible pore domain but is sufficient for expression of a voltage-sensitive proton-selective ion channel activity. H(v)1 currents are activated at depolarizing voltages, sensitive to the transmembrane pH gradient, H+-selective, and Zn2+-sensitive. Mutagenesis of H(v)1 identified three arginine residues in S4 that regulate channel gating and two histidine residues that are required for extracellular inhibition of H(v)1 by Zn2+. H(v)1 is expressed in immune tissues and manifests the characteristic properties of native proton conductances (G(vH+)). In phagocytic leukocytes, G(vH+) are required to support the oxidative burst that underlies microbial killing by the innate immune system. The data presented here identify H(v)1 as a long-sought voltage-gated H+ channel and establish H(v)1 as the founding member of a family of mammalian VSD proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Electric Conductivity
  • Humans
  • Hydrogen-Ion Concentration
  • Immune System / metabolism
  • Ion Channel Gating* / drug effects
  • Ion Channels / antagonists & inhibitors
  • Ion Channels / chemistry*
  • Ion Channels / genetics
  • Ion Channels / metabolism*
  • Ligands
  • Mutation / genetics
  • Protein Structure, Tertiary
  • Protons*
  • Zinc / pharmacology

Substances

  • Hv1 channel, human
  • Ion Channels
  • Ligands
  • Protons
  • Zinc