Opioid receptors mediate the actions of endogenous and exogenous opioids on many physiological processes, including the regulation of pain, respiratory drive, mood, and—in the case of κ-opioid receptor (κ-OR)—dysphoria and psychotomimesis. Here we report the crystal structure of the human κ-OR in complex with the selective antagonist JDTic, arranged in parallel dimers, at 2.9 Å resolution. The structure reveals important features of the ligand-binding pocket that contribute to the high affinity and subtype selectivity of JDTic for the human κ-OR. Modelling of other important κ-OR-selective ligands, including the morphinan-derived antagonists norbinaltorphimine and 5′-guanidinonaltrindole, and the diterpene agonist salvinorin A analogue RB-64, reveals both common and distinct features for binding these diverse chemotypes. Analysis of site-directed mutagenesis and ligand structure–activity relationships confirms the interactions observed in the crystal structure, thereby providing a molecular explanation for κ-OR subtype selectivity, and essential insights for the design of compounds with new pharmacological properties targeting the human κ-OR.
Structure of the human κ-opioid receptor in complex with JDTic
Wu, H., Wacker, D., Katritch, V., Mileni, M., Han, G., Vardy, E., Liu, W., Thompson, A., Huang, X-P., Carroll, F., Mascarella, S., Westkaemper, R., Mosier, P., Roth, B., Cherezov, V., & Stevens, R. (2012). Structure of the human κ-opioid receptor in complex with JDTic. Nature, 485(7398), 327 - 332. https://doi.org/10.1038/nature10939