Channels Potassium Permeation

Valda Vinson

Science, AAAS, Washington, DC 20005, USA

Two–pore domain potassium (K2P) channels conduct K⁺ ions across the plasma membrane of eukaryotic cells. They help to maintain the cellular resting potential, and their modulation can tune cellular excitability (see the Perspective by Poulsen and Nissen). Miller and Long describe a high-resolution crystal structure of the human K2P channel K2P1 (TWIK-1), and Brohawn et al. present a high-resolution structure of the lipid- and mechanosensitive human channel TRAAK. In both structures, an extracellular domain constricts the channel entrance so that K⁺ ions reach the selectivity filter through side portals. Openings in the transmembrane region expose the central cavity to the lipid bilayer, and a helix is kinked so that its C-terminal part lies in the cytosol-membrane interface. The structural features explain K2P conductance and gating and give insight into how the channels are regulated by diverse stimuli.

A. N. Miller, S. B. Long, Crystal structure of the human two–pore domain potassium channel K2P1. Science 335, 432–436 (2012). [Abstract] [Full Text]

S. G. Brohawn, J. del Mármol, R. MacKinnon, Crystal structure of the human K2P TRAAK, a lipid- and mechano-sensitive K⁺ ion channel. Science 335, 436–441 (2012). [Abstract] [Full Text]

H. Poulsen, P. Nissen, The inner workings of a dynamic duo. Science 335, 416–417 (2012). [Abstract] [Full Text]

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