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基本情報
登録情報 | データベース: PDB / ID: 5oyg | |||||||||
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タイトル | Structure of calcium-free mTMEM16A chloride channel at 4.06 A resolution | |||||||||
![]() | Anoctamin-1 | |||||||||
![]() | MEMBRANE PROTEIN / TMEM16 family / ion channel / cryo-EM | |||||||||
機能・相同性 | ![]() glial cell projection elongation / trachea development / mucus secretion / intracellularly calcium-gated chloride channel activity / voltage-gated chloride channel activity / Stimuli-sensing channels / chloride transport / chloride channel activity / detection of temperature stimulus involved in sensory perception of pain / chloride channel complex ...glial cell projection elongation / trachea development / mucus secretion / intracellularly calcium-gated chloride channel activity / voltage-gated chloride channel activity / Stimuli-sensing channels / chloride transport / chloride channel activity / detection of temperature stimulus involved in sensory perception of pain / chloride channel complex / positive regulation of insulin secretion involved in cellular response to glucose stimulus / chloride transmembrane transport / regulation of membrane potential / cell projection / establishment of localization in cell / cellular response to heat / presynaptic membrane / phospholipase C-activating G protein-coupled receptor signaling pathway / apical plasma membrane / external side of plasma membrane / glutamatergic synapse / protein homodimerization activity / metal ion binding / identical protein binding / plasma membrane 類似検索 - 分子機能 | |||||||||
生物種 | ![]() ![]() | |||||||||
手法 | 電子顕微鏡法 / 単粒子再構成法 / クライオ電子顕微鏡法 / 解像度: 4.06 Å | |||||||||
![]() | Paulino, C. / Kalienkova, V. / Lam, K.M. / Neldner, Y. / Dutzler, R. | |||||||||
資金援助 | ![]()
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![]() | ![]() タイトル: Activation mechanism of the calcium-activated chloride channel TMEM16A revealed by cryo-EM. 著者: Cristina Paulino / Valeria Kalienkova / Andy K M Lam / Yvonne Neldner / Raimund Dutzler / ![]() 要旨: The calcium-activated chloride channel TMEM16A is a ligand-gated anion channel that opens in response to an increase in intracellular Ca concentration. The protein is broadly expressed and ...The calcium-activated chloride channel TMEM16A is a ligand-gated anion channel that opens in response to an increase in intracellular Ca concentration. The protein is broadly expressed and contributes to diverse physiological processes, including transepithelial chloride transport and the control of electrical signalling in smooth muscles and certain neurons. As a member of the TMEM16 (or anoctamin) family of membrane proteins, TMEM16A is closely related to paralogues that function as scramblases, which facilitate the bidirectional movement of lipids across membranes. The unusual functional diversity of the TMEM16 family and the relationship between two seemingly incompatible transport mechanisms has been the focus of recent investigations. Previous breakthroughs were obtained from the X-ray structure of the lipid scramblase of the fungus Nectria haematococca (nhTMEM16), and from the cryo-electron microscopy structure of mouse TMEM16A at 6.6 Å (ref. 14). Although the latter structure disclosed the architectural differences that distinguish ion channels from lipid scramblases, its low resolution did not permit a detailed molecular description of the protein or provide any insight into its activation by Ca. Here we describe the structures of mouse TMEM16A at high resolution in the presence and absence of Ca. These structures reveal the differences between ligand-bound and ligand-free states of a calcium-activated chloride channel, and when combined with functional experiments suggest a mechanism for gating. During activation, the binding of Ca to a site located within the transmembrane domain, in the vicinity of the pore, alters the electrostatic properties of the ion conduction path and triggers a conformational rearrangement of an α-helix that comes into physical contact with the bound ligand, and thereby directly couples ligand binding and pore opening. Our study describes a process that is unique among channel proteins, but one that is presumably general for both functional branches of the TMEM16 family. | |||||||||
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構造の表示
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構造ビューア | 分子: ![]() ![]() |
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-検証レポート
文書・要旨 | ![]() | 1.2 MB | 表示 | ![]() |
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文書・詳細版 | ![]() | 1.3 MB | 表示 | |
XML形式データ | ![]() | 50.4 KB | 表示 | |
CIF形式データ | ![]() | 75.8 KB | 表示 | |
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-関連構造データ
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リンク
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集合体
登録構造単位 | ![]()
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要素
#1: タンパク質 | 分子量: 111058.992 Da / 分子数: 2 / 由来タイプ: 組換発現 / 由来: (組換発現) ![]() ![]() ![]() Has protein modification | Y | |
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-実験情報
-実験
実験 | 手法: 電子顕微鏡法 |
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EM実験 | 試料の集合状態: PARTICLE / 3次元再構成法: 単粒子再構成法 |
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試料調製
構成要素 | 名称: mTMEM16A in absence of calcium ions / タイプ: COMPLEX / 詳細: calcium-activated chloride channel / Entity ID: all / 由来: RECOMBINANT |
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分子量 | 値: 0.110916 MDa / 実験値: YES |
由来(天然) | 生物種: ![]() ![]() |
由来(組換発現) | 生物種: ![]() |
緩衝液 | pH: 7.5 / 詳細: 20 mM Hepes 150 mM NaCl <0.12% digitonin |
緩衝液成分 | 濃度: 20 mM / 名称: Hepes |
試料 | 濃度: 3.3 mg/ml / 包埋: NO / シャドウイング: NO / 染色: NO / 凍結: YES 詳細: full-length (wild-type isoform ac) deglycosylated mTMEM16A in absence of CaCl2 |
試料支持 | グリッドの材料: GOLD / グリッドのサイズ: 200 divisions/in. / グリッドのタイプ: Quantifoil R1.2/1.3 |
急速凍結 | 装置: FEI VITROBOT MARK IV / 凍結剤: ETHANE / 湿度: 100 % / 凍結前の試料温度: 288 K / 詳細: 2 ul sample volume 2-4 sec blotting time |
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電子顕微鏡撮影
実験機器 | ![]() モデル: Titan Krios / 画像提供: FEI Company |
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顕微鏡 | モデル: FEI TITAN KRIOS |
電子銃 | 電子線源: ![]() |
電子レンズ | モード: BRIGHT FIELD / 倍率(公称値): 36630 X / 倍率(補正後): 36630 X / 最大 デフォーカス(公称値): 3800 nm / 最小 デフォーカス(公称値): 500 nm / Calibrated defocus min: 500 nm / 最大 デフォーカス(補正後): 3800 nm / Cs: 2.7 mm / C2レンズ絞り径: 100 µm / アライメント法: COMA FREE |
試料ホルダ | 凍結剤: NITROGEN 試料ホルダーモデル: FEI TITAN KRIOS AUTOGRID HOLDER 最高温度: 100 K / 最低温度: 80 K |
撮影 | 平均露光時間: 15 sec. / 電子線照射量: 80 e/Å2 / 検出モード: SUPER-RESOLUTION フィルム・検出器のモデル: GATAN K2 SUMMIT (4k x 4k) 撮影したグリッド数: 3 / 実像数: 5063 詳細: Data were collected in an automated fashion using SerialEM47 on a K2 Summit detector (Gatan). The dataset in absence of calcium ions was obtained at a pixel size of 0.6825A in super- ...詳細: Data were collected in an automated fashion using SerialEM47 on a K2 Summit detector (Gatan). The dataset in absence of calcium ions was obtained at a pixel size of 0.6825A in super-resolution mode, a defocus range of -0.5 to -3.9 um, an exposure time of 15 sec and a sub-frame exposure time of 150 ms (100 frames) with an electron dose at the specimen level of 0.75-0.8 e-/A2/frame. The total accumulated dose on the specimen level was approximately 80 e-/A2. |
電子光学装置 | エネルギーフィルター名称: In-column Omega Filter エネルギーフィルター 上限: 10 eV / エネルギーフィルター 下限: -10 eV / エネルギーフィルタースリット幅: 20 eV |
画像スキャン | サンプリングサイズ: 5 µm / 横: 7420 / 縦: 7676 / 動画フレーム数/画像: 100 / 利用したフレーム数/画像: 1-100 |
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解析
ソフトウェア | 名称: REFMAC / バージョン: 5.8.0158 / 分類: 精密化 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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EMソフトウェア |
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画像処理 | 詳細: Fourier cropping (final pixel size 1.365 A), motion correction and dose-weighting of frames were performed by MotionCor2 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
CTF補正 | 詳細: The contrast transfer function (CTF) parameters were estimated on the movie frames by ctffind4.1 タイプ: PHASE FLIPPING AND AMPLITUDE CORRECTION | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
粒子像の選択 | 選択した粒子像数: 1349821 詳細: For the dataset collected in absence of calcium ions a total of 5063 dose-fractionated super-resolution images were recorded, 2 x 2 down-sampled by Fourier cropping (final pixel size 1.365A) ...詳細: For the dataset collected in absence of calcium ions a total of 5063 dose-fractionated super-resolution images were recorded, 2 x 2 down-sampled by Fourier cropping (final pixel size 1.365A) and subjected to motion correction and dose-weighting of frames by MotionCor2. The contrast transfer function (CTF) parameters were estimated on the movie frames by ctffind4.1. Images showing a strong drift, higher defocus than -3.8 um or a bad CTF estimation were discarded, From a total of 4,738 images (final pixel size 1.365 A) 1,349,821 particles were extracted with a box size of 256 pixels after auto-picking and initial round of 2D classification. Initial rounds of 2D and 3D classification, resulted in a set of 467,286 particles which where subjected to particle polishing, as described above, as well as final rounds of 3D classification. The final polished and auto-refined map was calculated from 195,465 particles derived from 4726 images with a resolution of 4.86 A before masking and 4.06 A after masking and was sharpened using an isotropic b-factor of -116 A2 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
3次元再構成 | 解像度: 4.06 Å / 解像度の算出法: FSC 0.143 CUT-OFF / 粒子像の数: 195465 / 対称性のタイプ: POINT | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
原子モデル構築 | プロトコル: RIGID BODY FIT | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
精密化 | 解像度: 4.06→120.12 Å / Cor.coef. Fo:Fc: 0.519 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
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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 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
原子変位パラメータ | Biso mean: 161.117 Å2
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精密化ステップ | サイクル: 1 / 合計: 11596 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
拘束条件 |
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