biostudies-literatureZhang HChinese Ministry of Science and Technology | Department of S and T for Social Development (Department of S&T for Social Development)China Postdoctoral Science FoundationNational Natural Science Foundation of China (National Science Foundation of China)1021-1036https://www.ebi.ac.uk/biostudies/studies/S-EPMC12689640biostudies-literatureUnknown35(12)Activation of the μ-opioid receptor (μOR) alleviates pain but also elicits adverse effects through diverse G proteins and β-arrestins. The structural details of μOR complexes with G_z and β-arrestins have not been determined, impeding a comprehensive understanding of μOR signaling plasticity. Here, we present the cryo-EM structures of the μOR-G_z and μOR-βarr1 complexes, revealing selective conformational preferences of μOR when engaged with specific downstream signaling transducers. Integrated receptor pharmacology, including high-resolution structural analysis, cell signaling assays, and molecular dynamics simulations, demonstrated that transmembrane helix 1 (TM1) acts as an allosteric regulator of μOR signaling bias through differential stabilization of the G<sub>i</Cell researchThe molecular basis of μ-opioid receptor signaling plasticity.PMC12689640321410042024M752856822710012019YFA05088009235330332430051Yang GShen QJi SYDong YZhu YQin JZhang HYang MZang SKChen LNWu HZhao MGuo JXi KZhang YYu TWang XXue JShen DDfalseThe molecular basis of μ-opioid receptor signaling plasticity.Activation of the μ-opioid receptor (μOR) alleviates pain but also elicits adverse effects through diverse G proteins and β-arrestins. The structural details of μOR complexes with G_z and β-arrestins have not been determined, impeding a comprehensive understanding of μOR signaling plasticity. Here, we present the cryo-EM structures of the μOR-G_z and μOR-βarr1 complexes, revealing selective conformational preferences of μOR when engaged with specific downstream signaling transducers. Integrated receptor pharmacology, including high-resolution structural analysis, cell signaling assays, and molecular dynamics simulations, demonstrated that transmembrane helix 1 (TM1) acts as an allosteric regulator of μOR signaling bias through differential stabilization of the G<sub>i</2025-01-01T00:00:00Z2025 Dec2026-07-15T06:36:44.457Z2026-06-30T03:23:41.451ZS-EPMC126896404119900510.1038/s41422-025-01191-8