Science 27: 436–441 (January 27, 2012)

Science 335: 436–441
Crystal structure of the human K2P TRAAK, a lipid- and mechano-sensitive K⁺ ion channel
Stephen G. Brohawn, Josefina del Mármol and Roderick MacKinnon

We present the crystal structure of human TRAAK at a resolution of 3.8 angstroms. The channel comprises two protomers, each containing two distinct pore domains, which create a two-fold symmetric K⁺ channel. The extracellular surface features a helical cap, 35 angstroms tall, that creates a bifurcated pore entryway and accounts for the insensitivity of two–pore domain K⁺ channels to inhibitory toxins. Two diagonally opposed gate-forming inner helices form membrane-interacting structures that may underlie this channel’s sensitivity to chemical and mechanical properties of the cell membrane.