- PDB-8ijl: Cyo-EM structure of wildtype non-gastric proton pump in the prese... -
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データベース: PDB / ID: 8ijl
タイトル
Cyo-EM structure of wildtype non-gastric proton pump in the presence of Na+, AlF and ADP
要素
(Sodium/potassium-transporting ATPase subunit ...) x 2
キーワード
MEMBRANE PROTEIN / P-type ATPase / P2-type ATPase
機能・相同性
機能・相同性情報
Basigin interactions / Ion transport by P-type ATPases / P-type potassium:proton transporter activity / positive regulation of sodium ion export across plasma membrane / positive regulation of potassium ion import across plasma membrane / metal ion transport / P-type sodium:potassium-exchanging transporter activity / sodium:potassium-exchanging ATPase complex / membrane repolarization / regulation of pH ...Basigin interactions / Ion transport by P-type ATPases / P-type potassium:proton transporter activity / positive regulation of sodium ion export across plasma membrane / positive regulation of potassium ion import across plasma membrane / metal ion transport / P-type sodium:potassium-exchanging transporter activity / sodium:potassium-exchanging ATPase complex / membrane repolarization / regulation of pH / sodium ion export across plasma membrane / intracellular potassium ion homeostasis / regulation of calcium ion transmembrane transport / potassium ion homeostasis / intracellular sodium ion homeostasis / regulation of cardiac muscle contraction by calcium ion signaling / relaxation of cardiac muscle / Ion homeostasis / sodium ion transport / organelle membrane / potassium ion import across plasma membrane / monoatomic cation transmembrane transport / ATPase activator activity / blastocyst development / intercalated disc / lateral plasma membrane / sperm flagellum / sodium ion transmembrane transport / ATP metabolic process / cardiac muscle contraction / T-tubule / protein localization to plasma membrane / potassium ion transport / caveola / sarcolemma / intracellular calcium ion homeostasis / protein-macromolecule adaptor activity / ATPase binding / regulation of gene expression / basolateral plasma membrane / response to hypoxia / protein stabilization / cell adhesion / protein heterodimerization activity / apical plasma membrane / innate immune response / protein kinase binding / ATP hydrolysis activity / ATP binding / membrane / metal ion binding / plasma membrane 類似検索 - 分子機能
ジャーナル: Biochim Biophys Acta Mol Cell Res / 年: 2023 タイトル: An unusual conformation from Na-sensitive non-gastric proton pump mutants reveals molecular mechanisms of cooperative Na-binding. 著者: Kazuhiro Abe / Tomohiro Nishizawa / Pablo Artigas / 要旨: The Na,K-ATPase (NKA) and non-gastric H,K- ATPase (ngHKA) share ~65 % sequence identity, and nearly identical catalytic cycles. These pumps alternate between inward-facing (E1) and outward-facing ...The Na,K-ATPase (NKA) and non-gastric H,K- ATPase (ngHKA) share ~65 % sequence identity, and nearly identical catalytic cycles. These pumps alternate between inward-facing (E1) and outward-facing (E2) conformations and differ in their exported substrate (Na or H) and stoichiometries (3 Na:2 K or 1 H:1 K). We reported that structures of the NKA-mimetic ngHKA mutant K794S/A797P/W940/R949C (SPWC) with 2 K occluded in E2-P and 3 Na-bound in E1·ATP states were nearly identical to NKA structures in equivalent states. Here we report the cryo-EM structures of K794A and K794S, two poorly-selective ngHKA mutants, under conditions to stabilize the E1·ATP state. Unexpectedly, the structures show a hybrid with both E1- and E2-like structural features. While transmembrane segments TM1-TM3 and TM4's extracellular half adopted an E2-like conformation, the rest of the protein assumed an E1 configuration. Two spherical densities, likely bound Na, were observed at cation-binding sites I and III, without density at site II. This explains the E2-like conformation of TM4's exoplasmic half. In NKA, oxygen atoms derived from the unwound portion of TM4 coordinated Na at site II. Thus, the lack of Na at site II of K794A/S prevents the luminal portion of TM4 from taking an E1-like position. The K794A structure also suggests that incomplete coordination of Na at site III induces the halfway rotation of TM6, which impairs Na-binding at the site II. Thus, our observations provide insight into the molecular mechanism of E2-E1 transition and cooperative Na-binding in the NKA and other related cation pumps.