cellular response to water deprivation / renal water transport / glycerol transmembrane transporter activity / lumenal side of membrane / water transmembrane transporter activity / Passive transport by Aquaporins / glycerol transmembrane transport / cellular response to mercury ion / water transport / water channel activity ...cellular response to water deprivation / renal water transport / glycerol transmembrane transporter activity / lumenal side of membrane / water transmembrane transporter activity / Passive transport by Aquaporins / glycerol transmembrane transport / cellular response to mercury ion / water transport / water channel activity / metanephric collecting duct development / transport vesicle membrane / renal water homeostasis / cellular response to copper ion / actin filament organization / recycling endosome / Vasopressin regulates renal water homeostasis via Aquaporins / basolateral plasma membrane / protein homotetramerization / apical plasma membrane / perinuclear region of cytoplasm / Golgi apparatus / extracellular exosome / membrane / plasma membrane 類似検索 - 分子機能
Aquaporin transporter / Major intrinsic protein, conserved site / MIP family signature. / Major intrinsic protein / Major intrinsic protein / Aquaporin-like 類似検索 - ドメイン・相同性
ジャーナル: J Struct Biol / 年: 2023 タイトル: Structural analysis of the water channel AQP2 by single-particle cryo-EM. 著者: Akiko Kamegawa / Shota Suzuki / Hiroshi Suzuki / Kouki Nishikawa / Nobutaka Numoto / Yoshinori Fujiyoshi / 要旨: Water channels, which are small membrane proteins almost entirely buried in lipid membranes, are challenging research targets for single-particle cryo-electron microscopy (cryo-EM), a powerful ...Water channels, which are small membrane proteins almost entirely buried in lipid membranes, are challenging research targets for single-particle cryo-electron microscopy (cryo-EM), a powerful technique routinely used to determine the structures of membrane proteins. Because the single-particle method enables structural analysis of a whole protein with flexible parts that interfere with crystallization, we have focused our efforts on analyzing water channel structures. Here, utilizing this system, we analyzed the structure of full-length aquaporin-2 (AQP2), a primary regulator of vasopressin-dependent reabsorption of water at the renal collecting ducts. The 2.9 Å resolution map revealed a cytoplasmic extension of the cryo-EM density that was presumed to be the highly flexible C-terminus at which the localization of AQP2 is regulated in the renal collecting duct cells. We also observed a continuous density along the common water pathway inside the channel pore and lipid-like molecules at the membrane interface. Observations of these constructions in the AQP2 structure analyzed without any fiducial markers (e.g., a rigidly bound antibody) indicate that single-particle cryo-EM will be useful for investigating water channels in native states as well as in complexes with chemical compounds.