Crystal structure of the human K2P TRAAK, a lipid- and mechano-sensitive K+ ion channel.

Science. 2012 Jan 27; 335(6067): 436-41
Brohawn SG, del Mrmol J, MacKinnon R

TRAAK channels, members of the two-pore domain K(+) (potassium ion) channel family K2P, are expressed almost exclusively in the nervous system and control the resting surface potential. Their gating is sensitive to polyunsaturated fatty acids, automatic deformation of the membrane, and heat changes. Physiologically, these channels appear to control the noxious input starting point for heat and pressure sensitivity in dorsal root ganglia neurons. We present the crystal structure of tellurian TRAAK at the resolution of 3.8 angstroms. The channel comprises dual protomers, any containing dual distinct pore domains, which create the two-fold symmetric K(+) channel. The extracellular surface features the helical cap, 35 angstroms tall, that creates the bifurcated pore entryway and accounts for the insensitivity of two-pore domain K(+) channels to inhibitory toxins. Two diagonally against gate-forming inner helices form membrane-interacting structures that might underlie this channel's sensitivity to chemical and automatic properties of the cell membrane.

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