Noradrenaline, also known as norepinephrine, has a wide range of activities and effects on most brain cell types¹. Its reuptake from the synaptic cleft heavily relies on the noradrenaline transporter (NET) located in the presynaptic membrane². Here we report the cryo-electron microscopy (cryo-EM) structures of the human NET in both its apo state and when bound to substrates or antidepressant drugs, with resolutions ranging from 2.5 Å to 3.5 Å. The two substrates, noradrenaline and dopamine, display a similar binding mode within the central substrate binding site (S1) and within a newly identified extracellular allosteric site (S2). Four distinct antidepressants, namely, atomoxetine, desipramine, bupropion and escitalopram, occupy the S1 site to obstruct substrate transport in distinct conformations. Moreover, a potassium ion was observed within sodium-binding site 1 in the structure of the NET bound to desipramine under the KCl condition. Complemented by structural-guided biochemical analyses, our studies reveal the mechanism of substrate recognition, the alternating access of NET, and elucidate the mode of action of the four antidepressants.

去甲肾上腺素，也称为去甲肾上腺素，对大多数脑细胞类型具有广泛的活性和影响¹ 。它从突触间隙的再摄取很大程度上依赖于位于突触前膜的去甲肾上腺素转运蛋白 (NET) ² 。在这里，我们报告了人类 NET 在其 apo 状态以及与底物或抗抑郁药物结合时的冷冻电子显微镜 (cryo-EM) 结构，分辨率范围为 2.5 Å 至 3.5 Å。去甲肾上腺素和多巴胺这两种底物在中心底物结合位点 (S1) 和新识别的细胞外变构位点 (S2) 内显示出相似的结合模式。四种不同的抗抑郁药，即阿托莫西汀、地昔帕明、安非他酮和艾司西酞普兰，占据 S1 位点以阻碍不同构象的底物转运。此外，在KCl条件下与地昔帕明结合的NET结构中的钠结合位点1内观察到钾离子。辅以结构引导的生化分析，我们的研究揭示了底物识别机制、NET 的交替访问，并阐明了四种抗抑郁药的作用模式。