人类溶负载体有机阴离子转运肽家族（OATPs）成员作为运输体，对包括内源性代谢物和临床药物（如胆盐、类固醇、甲状腺激素、他汀类药物、抗生素、抗病毒药物和抗癌药物）在内的大量两性有机阴离子起到运输作用。OATP1B1在将这些物质转运到肝脏进行肝清除中起着至关重要的作用。FDA和EMA建议对涉及OATP1B1的药物相互作用（DDIs）进行体外测试。然而，OATPs的结构和作用机制仍然不清楚。在本研究中，我们确定了人类OATP1B1与代表性内源性代谢物（胆红素和雌酮-3-硫酸盐）、临床药物（西酸他韦）和荧光指示剂（2'，7'-二氯荧光素）结合的冷冻电镜结构，包括内向开放和外向开放状态。这些结构揭示了主要和次要底物结合口袋以及运输过程中的构象变化。结合突变研究和分子动力学模拟，我们的工作全面阐明了OATP1B1的转运机制，并为涉及OATP1B1的DDI预测提供了结构基础，这将极大促进我们对OATPs的理解。©2023. 作者(们)。

Members of the solute carrier organic anion transporting polypeptide (OATPs) family function as transporters for a large variety of amphipathic organic anions including endogenous metabolites and clinical drugs, such as bile salts, steroids, thyroid hormones, statins, antibiotics, antivirals, and anticancer drugs. OATP1B1 plays a vital role in transporting such substances into the liver for hepatic clearance. FDA and EMA recommend conducting in vitro testing of drug-drug interactions (DDIs) involving OATP1B1. However, the structure and working mechanism of OATPs still remains elusive. In this study, we determined cryo-EM structures of human OATP1B1 bound with representative endogenous metabolites (bilirubin and estrone-3-sulfate), a clinical drug (simeprevir), and a fluorescent indicator (2',7'-dichlorofluorescein), in both outward- and inward-open states. These structures reveal major and minor substrate binding pockets and conformational changes during transport. In combination with mutagenesis studies and molecular dynamics simulations, our work comprehensively elucidates the transport mechanism of OATP1B1 and provides the structural basis for DDI predictions involving OATP1B1, which will greatly promote our understanding of OATPs.© 2023. The Author(s).