National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
GM13230704
米国
National Institutes of Health/National Cancer Institute (NIH/NCI)
CA008748
米国
National Institutes of Health/National Cancer Institute (NIH/NCI)
CA243235
米国
引用
ジャーナル: Nat Commun / 年: 2023 タイトル: Structural titration reveals Ca-dependent conformational landscape of the IP receptor. 著者: Navid Paknejad / Vinay Sapuru / Richard K Hite / 要旨: Inositol 1,4,5-trisphosphate receptors (IPRs) are endoplasmic reticulum Ca channels whose biphasic dependence on cytosolic Ca gives rise to Ca oscillations that regulate fertilization, cell division ...Inositol 1,4,5-trisphosphate receptors (IPRs) are endoplasmic reticulum Ca channels whose biphasic dependence on cytosolic Ca gives rise to Ca oscillations that regulate fertilization, cell division and cell death. Despite the critical roles of IPR-mediated Ca responses, the structural underpinnings of the biphasic Ca dependence that underlies Ca oscillations are incompletely understood. Here, we collect cryo-EM images of an IPR with Ca concentrations spanning five orders of magnitude. Unbiased image analysis reveals that Ca binding does not explicitly induce conformational changes but rather biases a complex conformational landscape consisting of resting, preactivated, activated, and inhibited states. Using particle counts as a proxy for relative conformational free energy, we demonstrate that Ca binding at a high-affinity site allows IPRs to activate by escaping a low-energy resting state through an ensemble of preactivated states. At high Ca concentrations, IPRs preferentially enter an inhibited state stabilized by a second, low-affinity Ca binding site. Together, these studies provide a mechanistic basis for the biphasic Ca-dependence of IPR channel activity.
名称: Human Type 3 IP3 Receptor / タイプ: complex / ID: 1 / 親要素: 0 / 含まれる分子: all 詳細: In the presence of saturating IP3, ATP, and Ca2+ titrated from 1 nM to 10 um
由来(天然)
生物種: Homo sapiens (ヒト)
分子量
理論値: 1.2 MDa
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分子 #1: Human Type 3 IP3 Receptor
分子
名称: Human Type 3 IP3 Receptor / タイプ: protein_or_peptide / ID: 1 / 光学異性体: LEVO
pH: 8 詳細: 120 mM NaCl, 50 mM Tris-HCl, pH 8.0, 0.02% LMNG, 2 mM dithiothreitol, 2 mM EDTA, 2 mM EGTA, 2 mM BAPTA, 2 mM HEDTA, 1 mM ATP, 500 uM fluorinated fos-choline-8, 3 mM free Mg2+, 1-10000 nM free Ca2+
凍結
凍結剤: ETHANE / チャンバー内湿度: 90 % / チャンバー内温度: 277 K / 装置: FEI VITROBOT MARK IV 詳細: Custom-made calcium free blotting paper (see publication for details)..
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電子顕微鏡法
顕微鏡
FEI TITAN KRIOS
撮影
フィルム・検出器のモデル: GATAN K3 (6k x 4k) / 撮影したグリッド数: 6 / 実像数: 17733 / 平均露光時間: 3.0 sec. / 平均電子線量: 66.0 e/Å2 詳細: Images were collected at 0.826 A/px magnification on an FEI Krios with Gatan K3 detector at 15 e-/pix/sec with 3 sec exposure (0.05 sec/frame) for a total dose of 66 e-/A2 in automated ...詳細: Images were collected at 0.826 A/px magnification on an FEI Krios with Gatan K3 detector at 15 e-/pix/sec with 3 sec exposure (0.05 sec/frame) for a total dose of 66 e-/A2 in automated fashion using SerialEM. Five datasets were collected during the same session for each Ca2+ concentration on a series of grids that were prepared sequentially resulting in 637 movies at 1 nM, 2150 movies at 10 nM, 6126 movies at 100 nM, 1372 movies at 1 uM, and 3136 movies at 10 uM. A sixth dataset of 4312 movies collected at nominal 100 nM free Ca2+ from a grid prepared later in the sequence was collected as a technical replicate to assess experimental error.