Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.
Biophysics Program, Stanford University, Stanford, CA, USA.
Nature. 2019 Aug;572(7770):488-492. doi: 10.1038/s41586-019-1438-2. Epub 2019 Jul 31.
Cation-chloride cotransporters (CCCs) mediate the electroneutral transport of chloride, potassium and/or sodium across the membrane. They have critical roles in regulating cell volume, controlling ion absorption and secretion across epithelia, and maintaining intracellular chloride homeostasis. These transporters are primary targets for some of the most commonly prescribed drugs. Here we determined the cryo-electron microscopy structure of the Na-K-Cl cotransporter NKCC1, an extensively studied member of the CCC family, from Danio rerio. The structure defines the architecture of this protein family and reveals how cytosolic and transmembrane domains are strategically positioned for communication. Structural analyses, functional characterizations and computational studies reveal the ion-translocation pathway, ion-binding sites and key residues for transport activity. These results provide insights into ion selectivity, coupling and translocation, and establish a framework for understanding the physiological functions of CCCs and interpreting disease-related mutations.
阳离子-氯离子共转运体（CCCs）介导氯离子、钾离子和/或钠离子在膜中的电中性转运。它们在调节细胞体积、控制上皮细胞内外离子吸收和分泌以及维持细胞内氯离子稳态方面发挥着关键作用。这些转运体是一些最常用处方药的主要靶点。在这里，我们确定了来自斑马鱼的 Na-K-Cl 共转运体 NKCC1 的冷冻电镜结构，NKCC1 是 CCC 家族中研究得非常广泛的成员之一。该结构定义了该蛋白家族的结构，并揭示了细胞质和跨膜结构域如何战略性地定位以进行通讯。结构分析、功能表征和计算研究揭示了离子转运途径、离子结合位点和关键残基的转运活性。这些结果为离子选择性、偶联和转运提供了深入的了解，并为理解 CCC 的生理功能和解释与疾病相关的突变奠定了框架。
