- EMDB-20790: Cryo-EM structure of human CALHM2 gap junction -
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基本情報
登録情報
データベース: EMDB / ID: EMD-20790
タイトル
Cryo-EM structure of human CALHM2 gap junction
マップデータ
Unsharpened final map refined with a soft solvent mask. Improved resolution for the well-defined parts of the protein, yet incomplete densities for the highly flexible regions such as S1.
試料
複合体: human CALHM2
タンパク質・ペプチド: Calcium homeostasis modulator protein 2
キーワード
calcium homeostasis modulator / CALHM2 / gap junction / TRANSPORT PROTEIN
機能・相同性
機能・相同性情報
regulation of microglial cell activation / ATP export / calcium ion import / monoatomic cation channel activity / regulation of synaptic plasticity / positive regulation of apoptotic process / plasma membrane 類似検索 - 分子機能
ジャーナル: Nature / 年: 2019 タイトル: The structures and gating mechanism of human calcium homeostasis modulator 2. 著者: Wooyoung Choi / Nicolina Clemente / Weinan Sun / Juan Du / Wei Lü / 要旨: Calcium homeostasis modulators (CALHMs) are voltage-gated, Ca-inhibited nonselective ion channels that act as major ATP release channels, and have important roles in gustatory signalling and neuronal ...Calcium homeostasis modulators (CALHMs) are voltage-gated, Ca-inhibited nonselective ion channels that act as major ATP release channels, and have important roles in gustatory signalling and neuronal toxicity. Dysfunction of CALHMs has previously been linked to neurological disorders. Here we present cryo-electron microscopy structures of the human CALHM2 channel in the Ca-free active or open state and in the ruthenium red (RUR)-bound inhibited state, at resolutions up to 2.7 Å. Our work shows that purified CALHM2 channels form both gap junctions and undecameric hemichannels. The protomer shows a mirrored arrangement of the transmembrane domains (helices S1-S4) relative to other channels with a similar topology, such as connexins, innexins and volume-regulated anion channels. Upon binding to RUR, we observed a contracted pore with notable conformational changes of the pore-lining helix S1, which swings nearly 60° towards the pore axis from a vertical to a lifted position. We propose a two-section gating mechanism in which the S1 helix coarsely adjusts, and the N-terminal helix fine-tunes, the pore size. We identified a RUR-binding site near helix S1 that may stabilize this helix in the lifted conformation, giving rise to channel inhibition. Our work elaborates on the principles of CALHM2 channel architecture and symmetry, and the mechanism that underlies channel inhibition.
ダウンロード / ファイル: emd_20790.map.gz / 形式: CCP4 / 大きさ: 149.9 MB / タイプ: IMAGE STORED AS FLOATING POINT NUMBER (4 BYTES)
注釈
Unsharpened final map refined with a soft solvent mask. Improved resolution for the well-defined parts of the protein, yet incomplete densities for the highly flexible regions such as S1.