3R65

MthK channel pore E92Q mutant

3R65 の概要

• エントリーDOI: 10.2210/pdb3r65/pdb
• 関連するPDBエントリー: 3LDC
• 分子名称: Calcium-gated potassium channel mthK, POTASSIUM ION (3 entities in total)
• 機能のキーワード: trans-membrane, ion channel, potassium ion, membrane, membrane protein
• 由来する生物種: Methanothermobacter thermautotrophicus str. Delta H
• 細胞内の位置: Cell membrane; Multi-pass membrane protein: O27564
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 9189.99

構造登録者

Shi, N.,Zeng, W.,Ye, S.,Li, Y.,Jiang, Y. (登録日: 2011-03-21, 公開日: 2012-02-01, 最終更新日: 2023-09-13)

主引用文献

Shi, N.,Zeng, W.,Ye, S.,Li, Y.,Jiang, Y.
Crucial points within the pore as determinants of K+ channel conductance and gating
J.Mol.Biol., 411:27-35, 2011

PubMed Abstract: While selective for K⁺, K⁺ channels vary significantly among their rate of ion permeation. Here, we probe the effect of steric hindrance and electrostatics within the ion conduction pathway on K⁺ permeation in the MthK K⁺ channel using structure-based mutagenesis combined with single-channel electrophysiology and X-ray crystallography. We demonstrate that changes in side-chain size and polarity at Ala88, which forms the constriction point of the open MthK pore, have profound effects on single-channel conductance as well as open probability. We also reveal that the negatively charged Glu92s at the intracellular entrance of the open pore form an electrostatic trap, which stabilizes a hydrated K⁺ and facilitates ion permeation. This electrostatic attraction is also responsible for intracellular divalent blockage, which renders the channel inward rectified in the presence of Ca²⁺. In light of the high structural conservation of the selectivity filter, the size and chemical environment differences within the portion of the ion conduction pathway other than the filter are likely the determinants for the conductance variations among K⁺ channels.

PubMed: 21554888
DOI: 10.1016/j.jmb.2011.04.058

実験手法

X-RAY DIFFRACTION (1.8 Å)