ジャーナル: Cell / 年: 2017 タイトル: Structural Titration of Slo2.2, a Na-Dependent K Channel. 著者: Richard K Hite / Roderick MacKinnon / 要旨: The stable structural conformations that occur along the complete reaction coordinate for ion channel opening have never been observed. In this study, we describe the equilibrium ensemble of ...The stable structural conformations that occur along the complete reaction coordinate for ion channel opening have never been observed. In this study, we describe the equilibrium ensemble of structures of Slo2.2, a neuronal Na-activated K channel, as a function of the Na concentration. We find that Slo2.2 exists in multiple closed conformations whose relative occupancies are independent of Na concentration. An open conformation emerges from an ensemble of closed conformations in a highly Na-dependent manner, without evidence of Na-dependent intermediates. In other words, channel opening is a highly concerted, switch-like process. The midpoint of the structural titration matches that of the functional titration. A maximum open conformation probability approaching 1.0 and maximum functional open probability approaching 0.7 imply that, within the class of open channels, there is a subclass that is not permeable to ions.
選択した粒子像数: 160000 / 詳細: Manual particle selection in RELION
対称性
点対称性: C4 (4回回転対称)
3次元再構成
解像度: 3.76 Å / 解像度の算出法: FSC 0.143 CUT-OFF / 粒子像の数: 130000 / アルゴリズム: FOURIER SPACE / クラス平均像の数: 8 / 対称性のタイプ: POINT
原子モデル構築
プロトコル: AB INITIO MODEL
精密化
解像度: 3.76→3.76 Å / Cor.coef. Fo:Fc: 0.86 / SU B: 117.148 / SU ML: 0.982 立体化学のターゲット値: MAXIMUM LIKELIHOOD WITH PHASES 詳細: HYDROGENS HAVE BEEN ADDED IN THE RIDING POSITIONS /
Rfactor
反射数
%反射
Rwork
0.399
-
-
obs
0.399
23056
100 %
溶媒の処理
イオンプローブ半径: 0.8 Å / 減衰半径: 0.8 Å / VDWプローブ半径: 1.2 Å / 溶媒モデル: MASK