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Potassium channels are dynamic proteins that undergo large conformational changes to regulate the flow of K(+) ions across the cell membrane. Understanding the gating mechanism of these channels therefore requires methods for probing channel structure in both their open and closed conformations. Radiolytic footprinting is used to study the gating mechanism of the inwardly-rectifying potassium channel KirBac3.1. The purified protein stabilized in either open or closed conformations was exposed to focused synchrotron X-ray beams on millisecond timescales to modify solvent accessible amino acid side chains. These modifications were identified and quantified using high-resolution mass spectrometry. The differences observed between the closed and open states were then used to reveal local conformational changes that occur during channel gating. The results provide support for a proposed gating mechanism of the Kir channel and demonstrate a method of probing the dynamic gating mechanism of other integral membrane proteins and ion channels.

Original publication

DOI

10.1016/j.str.2010.04.012

Type

Journal article

Journal

Structure

Publication Date

14/07/2010

Volume

18

Pages

839 - 846

Keywords

Ion Channel Gating, Mass Spectrometry, Models, Molecular, Potassium Channels, Inwardly Rectifying, Protein Conformation, Pulse Radiolysis, Synchrotrons