A voltage sensor-domain protein is a voltage-gated proton channel.
Voltage-gated proton channels have been widely observed but have not been identified at a molecular level. Here we report that a four-transmembrane protein similar to the voltage-sensor domain of voltage-gated ion channels is a voltage-gated proton channel. Cells overexpressing this protein showed depolarization-induced outward currents accompanied by tail currents. Current reversal occured at equilibrium potentials for protons. The currents exhibited pH-dependent gating and zinc ion sensitivity, two features which are characteristic of voltage-gated proton channels. Responses of voltage dependence to sequence changes suggest that mouse voltage-sensor domain-only protein is itself a channel, rather than a regulator of another channel protein.
Section of Developmental Neurophysiology, Okazaki Institute for Integrative Bioscience, Higashiyama 5-1, Myodaiji-cho, Okazaki, Aichi 444-8787, Japan.
Mari
M
Sasaki
Masahiro
M
Takagi
Yasushi
Y
Okamura
D000818:Animals; D002460:Cell Line; D002938:Ciona intestinalis; D004553:Electric Conductivity; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015640:Ion Channel Gating; D007473:Ion Channels / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D008564:Membrane Potentials; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D018408:Patch-Clamp Techniques; D017434:Protein Structure, Tertiary; D011522:Protons; D014162:Transfection
D007473:Ion Channels; D011522:Protons