Norepinephrine transporter (NET; encoded by SLC6A2) reuptakes the majority of the released noradrenaline back to the presynaptic terminals, thereby affecting the synaptic noradrenaline level¹. Genetic mutations and dysregulation of NET are associated with a spectrum of neurological conditions in humans, making NET an important therapeutic target¹. However, the structure and mechanism of NET remain unclear. Here we provide cryogenic electron microscopy structures of the human NET (hNET) in three functional states—the apo state, and in states bound to the substrate meta-iodobenzylguanidine (MIBG) or the orthosteric inhibitor radafaxine. These structures were captured in an inward-facing conformation, with a tightly sealed extracellular gate and an open intracellular gate. The substrate MIBG binds at the centre of hNET. Radafaxine also occupies the substrate-binding site and might block the structural transition of hNET for inhibition. These structures provide insights into the mechanism of substrate recognition and orthosteric inhibition of hNET.

去甲肾上腺素转运蛋白（NET；由SLC6A2编码）将大部分释放的去甲肾上腺素重新摄取回突触前末梢，从而影响突触去甲肾上腺素水平¹ 。 NET 的基因突变和失调与人类的一系列神经系统疾病有关，这使得 NET 成为重要的治疗靶点¹ 。然而，NET的结构和机制仍不清楚。在这里，我们提供了人类 NET (hNET) 在三种功能状态下的低温电子显微镜结构——apo 状态，以及与底物间碘苄基胍 (MIBG) 或正构抑制剂 radafaxine 结合的状态。这些结构以面向内的构象捕获，具有紧密密封的细胞外门和开放的细胞内门。底物 MIBG 结合在 hNET 的中心。 Radafaxine 还占据底物结合位点，并可能阻断 hNET 的结构转变以实现抑制。这些结构提供了对 hNET 的底物识别和正位抑制机制的见解。