ジャーナル: Nature / 年: 2015 タイトル: Gating machinery of InsP3R channels revealed by electron cryomicroscopy. 著者: Guizhen Fan / Matthew L Baker / Zhao Wang / Mariah R Baker / Pavel A Sinyagovskiy / Wah Chiu / Steven J Ludtke / Irina I Serysheva / 要旨: Inositol-1,4,5-trisphosphate receptors (InsP3Rs) are ubiquitous ion channels responsible for cytosolic Ca(2+) signalling and essential for a broad array of cellular processes ranging from contraction ...Inositol-1,4,5-trisphosphate receptors (InsP3Rs) are ubiquitous ion channels responsible for cytosolic Ca(2+) signalling and essential for a broad array of cellular processes ranging from contraction to secretion, and from proliferation to cell death. Despite decades of research on InsP3Rs, a mechanistic understanding of their structure-function relationship is lacking. Here we present the first, to our knowledge, near-atomic (4.7 Å) resolution electron cryomicroscopy structure of the tetrameric mammalian type 1 InsP3R channel in its apo-state. At this resolution, we are able to trace unambiguously ∼85% of the protein backbone, allowing us to identify the structural elements involved in gating and modulation of this 1.3-megadalton channel. Although the central Ca(2+)-conduction pathway is similar to other ion channels, including the closely related ryanodine receptor, the cytosolic carboxy termini are uniquely arranged in a left-handed α-helical bundle, directly interacting with the amino-terminal domains of adjacent subunits. This configuration suggests a molecular mechanism for allosteric regulation of channel gating by intracellular signals.
全体 : Inositol 1,4,5-trisphosphate receptor, type 1
全体
名称: Inositol 1,4,5-trisphosphate receptor, type 1
要素
試料: Inositol 1,4,5-trisphosphate receptor, type 1
タンパク質・ペプチド: Inositol 1,4,5-trisphosphate receptor
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超分子 #1000: Inositol 1,4,5-trisphosphate receptor, type 1
超分子
名称: Inositol 1,4,5-trisphosphate receptor, type 1 / タイプ: sample / ID: 1000 詳細: The sample was purified from rat cerebellum after solubilization with detergent; only freshly purified protein was used for cryo-EM visualization. 集合状態: tetramer / Number unique components: 1
pH: 7.4 詳細: 50 mM Tris-HCl, pH 7.4, 0.4% CHAPS, 150 mM NaCl, 1 mM DTT, 1 mM EGTA, 1 mM EDTA
グリッド
詳細: 400 mesh copper grids with thin carbon support
凍結
凍結剤: ETHANE / チャンバー内湿度: 100 % / チャンバー内温度: 120 K / 装置: FEI VITROBOT MARK IV / 手法: blot once for 3 seconds
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電子顕微鏡法
顕微鏡
FEI POLARA 300
温度
最低: 95 K / 最高: 102 K / 平均: 100 K
アライメント法
Legacy - 非点収差: Objective lens astigmatism was corrected at 100,000 times magnification.
特殊光学系
エネルギーフィルター - 名称: FEI
日付
2014年1月1日
撮影
カテゴリ: CCD / フィルム・検出器のモデル: GATAN K2 (4k x 4k) / デジタル化 - サンプリング間隔: 0.81 µm / 実像数: 4160 / 平均電子線量: 22 e/Å2 詳細: Every image is the sum of 30 frames recorded with a direct electron detector.
アルゴリズム: OTHER / 解像度のタイプ: BY AUTHOR / 解像度: 4.7 Å / 解像度の算出法: OTHER / ソフトウェア - 名称: RELION_1.3, EMAN_2.1 / 詳細: The final map was generated from 96,106 particles. / 使用した粒子像数: 96106