Abstract
The κ-opioid receptor (κOR) represents a promising non-addictive analgesic target due to its critical role in pain and reward pathways. Despite evidence of κOR dimerization, its molecular basis and pharmacological significance remain elusive. Here, we demonstrate stable κOR dimer formation in living cells and present cryo-electron microscopy structures of salvinorin A-bound κOR dimer complexed with two Gi proteins, revealing a parallel assembly distinct from previously characterized GPCR dimers that engage only single G protein. Multiple membrane lipids are positioned at the TM1-Helix 8 interface, where they make extensive contacts with both protomers and may contribute to the stability of the κOR dimer. Importantly, dimerization significantly enhances Gi protein recruitment to κOR in both potency and efficacy. We also demonstrate that salvinorin A, a non-nitrogenous agonist, binds similarly in monomeric and dimeric κOR, and identify Y3127.35 as a critical selectivity determinant across opioid receptors. These findings expand our understanding of opioid receptor pharmacology and signaling, providing a foundation for developing superior κOR-targeted therapeutics for pain and related disorders.
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Acknowledgements
The cryo-EM data of this study were collected at the Advanced Center for Electron Microscopy, Shanghai Institute of Materia Medica (SIMM). We thank all the staff at the center for their assistance in cryo-EM data collection. We also thank Shanghai Frontiers Science Center of Cellular Homeostasis and Human Diseases of Shanghai Jiao Tong University, School of Medicine, for the technical support.
Funding
This work was partially supported by grants from the National Natural Science Foundation of China (32400998 to Y.W., 32401002 to Y.W.Z., 32130022 and 82121005 to H.E.X., 32421003 to J.L.); the National Key R&D Program of China (2022YFA1302900 to H.E.X.; 2024YFA1307504 to Y.W.Z.); Strategic Priority Research Program of the Chinese Academy of Sciences Grant (No. XDB0830000, XDA0530000, XDB37030103 to H.E.X) ; Shanghai Municipal Science and Technology Major Project (2019SHZDZX02 to H.E.X.); the Shanghai Municipal Science and Technology Major Project (H.E.X.); the Young Elite Scientists Sponsorship Program by CAST (2023QNRC001 to Y.W.Z.); the Natural Science Foundation of Shanghai, China (23ZR1475300 to Y.W.Z.); the Sailing Program of Shanghai Venus Project (23YF1456700 to Y.W.Z.); the “Shanghai Jiao Tong University 2030” Project-Category C (WH510363003/017 to Y.W.Z.); the Innovative Research Team of High-Level Local Universities in Shanghai (Y.W.Z.); the Support of SANOFI Scholarship Program (Y.W.Z.); and the HE Research Fellowship (HERF2025011 to Y.W.Z.)
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H.E.X. is the founder of Cascade Pharmaceutics. All the other authors declare no competing interests.
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Zhao, Y., Xu, C., Wang, Y. et al. Structural characterization of kappa-opioid receptor dimer in complex with two G proteins. Nat Commun (2026). https://doi.org/10.1038/s41467-026-73615-x
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DOI: https://doi.org/10.1038/s41467-026-73615-x
