Biogenic monoamines, vital transmitters orchestrating neurological, endocrinal, and immunological functions^1-5, are stored in secretory vesicles by vesicular monoamine transporters (VMATs) for controlled quantal release^6,7. Harnessing proton antiport, VMATs enrich monoamines ~10,000-fold and sequester neurotoxicants to protect neurons^8-10. VMATs are targeted by an arsenal of therapeutic drugs and imaging agents to treat and monitor neurodegenerative disorders, hypertension, and drug addiction^1,8,11-16. However, the structural mechanisms underlying these actions remain elusive. Here, we report eight cryo-electron microscopy structures of human VMAT1 in unbound form and in complex with four monoamines, the Parkinsonism-inducing MPP⁺, the psychostimulant amphetamine, and the antihypertensive drug reserpine. Reserpine binding captures a cytoplasmic-open conformation, while other structures show a lumenal-open conformation stabilized by extensive gating interactions. The favored transition to this lumenal-open state contributes to monoamine accumulation, while protonation facilitates the cytoplasmic-open transition and concurrently prevents monoamine binding to avoid unintended depletion. Monoamines and neurotoxicants share a binding pocket possessing polar sites for specificity and a wrist-and-fist shape for versatility. Variations of this pocket explain substrate preferences across the SLC18 family. Overall, these structural insights and supporting functional studies elucidate the mechanism of vesicular monoamine transport and provide the basis to develop novel therapeutics for neurodegenerative diseases and substance abuse.

生物单胺是协调神经、内分泌和免疫功能的重要递质^1-5，通过囊泡单胺转运蛋白 (VMAT) 储存在分泌囊泡中，用于受控量子释放^6,7。利用质子反向转运，VMAT 将单胺富集约 10,000 倍并隔离神经毒物以保护神经元^8-10。VMAT 是一系列治疗药物和显像剂的靶标，用于治疗和监测神经退行性疾病、高血压和药物成瘾^1,8,11-16。然而，这些行为背后的结构机制仍然难以捉摸。在这里，我们报告了未结合形式的人 VMAT1 的八种冷冻电子显微镜结构，以及与四种单胺、帕金森病诱导 MPP ⁺、精神兴奋剂安非他明和抗高血压药物利血平的复合物。利血平结合捕获细胞质开放构象，而其他结构则显示出通过广泛的门控相互作用稳定的腔开放构象。向这种腔开放状态的有利转变有助于单胺积累，而质子化促进细胞质开放转变，同时防止单胺结合以避免意外消耗。单胺和神经毒剂共享一个结合袋，该结合袋具有用于特异性的极性位点和用于多功能性的手腕和拳头形状。该口袋的变化解释了 SLC18 系列的基板偏好。总体而言，这些结构见解和支持功能研究阐明了囊泡单胺转运机制，并为开发神经退行性疾病和药物滥用的新疗法提供了基础。