ジャーナル: Nature / 年: 2015 タイトル: Cryo-electron microscopy structure of the Slo2.2 Na(+)-activated K(+) channel. 著者: Richard K Hite / Peng Yuan / Zongli Li / Yichun Hsuing / Thomas Walz / Roderick MacKinnon / 要旨: Na(+)-activated K(+) channels are members of the Slo family of large conductance K(+) channels that are widely expressed in the brain, where their opening regulates neuronal excitability. These ...Na(+)-activated K(+) channels are members of the Slo family of large conductance K(+) channels that are widely expressed in the brain, where their opening regulates neuronal excitability. These channels fulfil a number of biological roles and have intriguing biophysical properties, including conductance levels that are ten times those of most other K(+) channels and gating sensitivity to intracellular Na(+). Here we present the structure of a complete Na(+)-activated K(+) channel, chicken Slo2.2, in the Na(+)-free state, determined by cryo-electron microscopy at a nominal resolution of 4.5 ångströms. The channel is composed of a large cytoplasmic gating ring, in which resides the Na(+)-binding site and a transmembrane domain that closely resembles voltage-gated K(+) channels. In the structure, the cytoplasmic domain adopts a closed conformation and the ion conduction pore is also closed. The structure reveals features that can explain the unusually high conductance of Slo channels and how contraction of the cytoplasmic gating ring closes the pore.
Manually picked particles with BOXER. 2D and 3D classification in RELION. Final map generated with FREALIGN using a mask that included only the transmembrane domain.
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想定した対称性 - 点群: C4 (4回回転対称) / アルゴリズム: OTHER / 解像度のタイプ: BY AUTHOR / 解像度: 5.2 Å / 解像度の算出法: OTHER / ソフトウェア - 名称: SPARX, RELION / 使用した粒子像数: 11303