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基本情報
登録情報 | データベース: PDB / ID: 6uxa | ||||||
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タイトル | MthK N-terminal truncation state 2 bound with calcium | ||||||
![]() | Calcium-gated potassium channel MthK | ||||||
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機能・相同性 | ![]() monoatomic cation transmembrane transporter activity / potassium ion transport / identical protein binding / ![]() ![]() 類似検索 - 分子機能 | ||||||
生物種 | ![]() ![]() ![]() | ||||||
手法 | ![]() ![]() ![]() | ||||||
![]() | Chen, F. / Crina, N. | ||||||
![]() | ![]() タイトル: Ball-and-chain inactivation in a calcium-gated potassium channel. 著者: Chen Fan / Nattakan Sukomon / Emelie Flood / Jan Rheinberger / Toby W Allen / Crina M Nimigean / ![]() ![]() ![]() 要旨: Inactivation is the process by which ion channels terminate ion flux through their pores while the opening stimulus is still present. In neurons, inactivation of both sodium and potassium channels is ...Inactivation is the process by which ion channels terminate ion flux through their pores while the opening stimulus is still present. In neurons, inactivation of both sodium and potassium channels is crucial for the generation of action potentials and regulation of firing frequency. A cytoplasmic domain of either the channel or an accessory subunit is thought to plug the open pore to inactivate the channel via a 'ball-and-chain' mechanism. Here we use cryo-electron microscopy to identify the molecular gating mechanism in calcium-activated potassium channels by obtaining structures of the MthK channel from Methanobacterium thermoautotrophicum-a purely calcium-gated and inactivating channel-in a lipid environment. In the absence of Ca, we obtained a single structure in a closed state, which was shown by atomistic simulations to be highly flexible in lipid bilayers at ambient temperature, with large rocking motions of the gating ring and bending of pore-lining helices. In Ca-bound conditions, we obtained several structures, including multiple open-inactivated conformations, further indication of a highly dynamic protein. These different channel conformations are distinguished by rocking of the gating rings with respect to the transmembrane region, indicating symmetry breakage across the channel. Furthermore, in all conformations displaying open channel pores, the N terminus of one subunit of the channel tetramer sticks into the pore and plugs it, with free energy simulations showing that this is a strong interaction. Deletion of this N terminus leads to functionally non-inactivating channels and structures of open states without a pore plug, indicating that this previously unresolved N-terminal peptide is responsible for a ball-and-chain inactivation mechanism. | ||||||
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構造ビューア | 分子: ![]() ![]() |
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PDBx/mmCIF形式 | ![]() | 290.7 KB | 表示 | ![]() |
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PDB形式 | ![]() | 204.3 KB | 表示 | ![]() |
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アーカイブディレクトリ | ![]() ![]() | HTTPS FTP |
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-関連構造データ
関連構造データ | ![]() 20931MC ![]() 6u5nC ![]() 6u5pC ![]() 6u5rC ![]() 6u68C ![]() 6u6dC ![]() 6u6eC ![]() 6u6hC ![]() 6uwnC ![]() 6ux4C ![]() 6ux7C ![]() 6uxbC M: このデータのモデリングに利用したマップデータ C: 同じ文献を引用 ( |
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集合体
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要素
#1: タンパク質 | 分子量: 37356.160 Da / 分子数: 8 / 由来タイプ: 組換発現 由来: (組換発現) ![]() ![]() ![]() 遺伝子: mthK, MTH_1520 / 発現宿主: ![]() ![]() ![]() |
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-実験情報
-実験
実験 | 手法: ![]() |
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EM実験 | 試料の集合状態: PARTICLE / 3次元再構成法: ![]() |
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試料調製
構成要素 | 名称: MthK N-terminal truncation / タイプ: COMPLEX / Entity ID: all / 由来: RECOMBINANT |
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分子量 | 実験値: NO |
由来(天然) | 生物種: ![]() ![]() ![]() |
由来(組換発現) | 生物種: ![]() ![]() ![]() |
緩衝液 | pH: 8.5 |
試料 | 包埋: NO / シャドウイング: NO / 染色![]() ![]() |
試料支持 | 詳細: unspecified |
急速凍結![]() | 凍結剤: ETHANE |
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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![]() |
撮影 | 電子線照射量: 1.425 e/Å2 / 検出モード: COUNTING フィルム・検出器のモデル: GATAN K2 SUMMIT (4k x 4k) |
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解析
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CTF補正![]() | タイプ: PHASE FLIPPING AND AMPLITUDE CORRECTION | ||||||||||||||||||||
対称性 | 点対称性![]() | ||||||||||||||||||||
3次元再構成![]() | 解像度: 4.5 Å / 解像度の算出法: FSC 0.143 CUT-OFF / 粒子像の数: 96834 / 対称性のタイプ: POINT |