title: Direct manipulation of a single potassium channel gate with an atomic force microscope probe.
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.
authors.affiliation: The Institute of Scientific and Industrial Research (ISIR-Sanken), Osaka University, 1-8 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Kitta
authors.forename: Toru
authors.initials: T
authors.lastname: Ide
authors.forename: Minako
authors.initials: M
authors.lastname: Hirano
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tanaka
authors.forename: Toshio
authors.initials: T
authors.lastname: Yanagida
authors.forename: Tomoji
authors.initials: T
authors.lastname: Kawai
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000648:ultrastructure*; D055119:Elastic Modulus; D015640:Ion Channel Gating; D008846:Micromanipulation / Q000379:methods*; D018625:Microscopy, Atomic Force / Q000379:methods*; D015221:Potassium Channels / Q000737:chemistry* / Q000648:ultrastructure*; D011487:Protein Conformation; D013314:Stress, Mechanical
chemical_list: D001426:Bacterial Proteins; D015221:Potassium Channels; C107790:prokaryotic potassium channel