image: The crystal structure of the human two-pore domain potassium ion channel TRAAK. TRAAK ion channels are expressed predominantly in the brain and nervous system where they control cellular electrical excitability. These channels are exquisitely sensitive to the chemical and mechanical properties of the cellular membrane in which they reside. They are activated by polyunsaturated fatty acids, including arachidonic acid, and by mechanical force. The TRAAK structure is the first of a two-pore domain potassium ion channel. It reveals an unprecedented helical cap structure on the extracellular side that prevents certain toxins from venomous animals from blocking the channel. The structure also shows an amphipathic helix on the cytoplasmic side that extends laterally like a tendril into the lipid bilayer and may be responsible for the channel's unique sensitivity to the membrane environment. This image relates to a paper that appeared in the Jan. 27, 2012, issue of Science, published by AAAS. The paper, by S.G. Brohawn at the Rockefeller University in New York, N.Y., and colleagues, was titled, “Crystal Structure of the Human K2P TRAAK, a Lipid- and Mechano-Sensitive K+ Ion Channel.” view more
Credit: [Image © <i>Science</i>/AAAS]