Direct Manipulation of a Single Potassium Channel Gate with an Atomic Force Microscope Probe

Authors

  • Mitsunori Kitta,

    1. The Institute of Scientific and Industrial Research (ISIR-Sanken), Osaka University, 1–8 Mihogaoka, Ibaraki, Osaka 567–0047, Japan
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    • These authors contributed equally to this work.

    • Research Institute for Ubiquitous Energy Devices, National Institute of Advanced Industrial Science and Technology, 1–8–31 Midorigaoka, Ikeda, Osaka 563–8577, Japan

  • Toru Ide,

    Corresponding author
    1. RIKEN Advanced Science Institute & Graduate School of Frontier Biosciences, Osaka University, 1–3 Yamadaoka, Suita, Osaka 565–0871, Japan
    • RIKEN Advanced Science Institute & Graduate School of Frontier Biosciences, Osaka University, 1–3 Yamadaoka, Suita, Osaka 565–0871, Japan.
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    • The Graduate School for the Creation of New Photonics Industries, 1955–1 Kurematsu Nishi-ku, Hamamatsu, Shizuoka 431–1202, Japan

  • Minako Hirano,

    1. RIKEN Quantitative Biology Center (QBiC) & Graduate School of Frontier Biosciences, Osaka University, 1–3 Yamadaoka, Suita, Osaka 565–0871, Japan
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  • Hiroyuki Tanaka,

    Corresponding author
    1. The Institute of Scientific and Industrial Research (ISIR-Sanken), Osaka University, 1–8 Mihogaoka, Ibaraki, Osaka 567–0047, Japan
    • The Institute of Scientific and Industrial Research (ISIR-Sanken), Osaka University, 1–8 Mihogaoka, Ibaraki, Osaka 567–0047, Japan
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  • Toshio Yanagida,

    1. RIKEN Quantitative Biology Center (QBiC) & Graduate School of Frontier Biosciences, Osaka University, 1–3 Yamadaoka, Suita, Osaka 565–0871, Japan
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  • Tomoji Kawai

    1. The Institute of Scientific and Industrial Research (ISIR-Sanken), Osaka University, 1–8 Mihogaoka, Ibaraki, Osaka 567–0047, Japan
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Abstract

Ion channels are membrane proteins that regulate cell functions by controlling the ion permeability of cell membranes. An ion channel contains an ion-selective pore that permeates ions and a sensor that senses a specific stimulus such as ligand binding to regulate the permeability. The detailed molecular mechanisms of this regulation, or gating, are unknown. Gating is thought to occur from conformational changes in the sensor domain in response to the stimulus, which results in opening the gate to permit ion conduction. Using an atomic force microscope and artificial bilayer system, a mechanical stimulus is applied to a potassium channel, and its gating is monitored in real time. The channel-open probability increases greatly when pushing the cytoplasmic domain toward the membrane. This result shows that a mechanical stimulus at the cytoplasmic domain causes changes in the gating and is the first to show direct evidence of coupling between conformational changes in the cytoplasmic domain and channel gating. This novel technology has the potential to be a powerful tool for investigating the activation dynamics in channel proteins.

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