NKCC and KCC transporters mediate coupled transport of Na⁺+K⁺+Cl⁻ and K⁺+Cl⁻ across the plasma membrane, thus regulating cell Cl⁻ concentration and cell volume and playing critical roles in transepithelial salt and water transport and in neuronal excitability. The function of these transporters has been intensively studied, but a mechanistic understanding has awaited structural studies of the transporters. Here, we present the cryo-electron microscopy (cryo-EM) structures of the two neuronal cation-chloride cotransporters human NKCC1 (SLC12A2) and mouse KCC2 (SLC12A5), along with computational analysis and functional characterization. These structures highlight essential residues in ion transport and allow us to propose mechanisms by which phosphorylation regulates transport activity.

NKCC 和 KCC 转运蛋白介导 Na ⁺ +K ⁺ +Cl ^-和 K ⁺ +Cl ^-跨质膜的耦合转运，从而调节细胞 Cl ^-浓度和细胞体积，并在跨上皮盐和水转运以及神经元兴奋性中起关键作用。这些转运蛋白的功能已得到深入研究，但对转运蛋白的结构研究尚待深入研究。在这里，我们展示了两种神经元阳离子-氯化物协同转运蛋白人类 NKCC1 (SLC12A2) 和小鼠 KCC2 (SLC12A5) 的冷冻电子显微镜 (cryo-EM) 结构，以及计算分析和功能表征。这些结构突出了离子运输中的重要残基，并允许我们提出磷酸化调节运输活动的机制。