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Cryo-EM structure of alpha1AAR-Nb6 complex bound to tamsulosin
Structural highlights
FunctionOPRK_HUMAN G-protein coupled opioid receptor that functions as receptor for endogenous alpha-neoendorphins and dynorphins, but has low affinity for beta-endorphins. Also functions as receptor for various synthetic opioids and for the psychoactive diterpene salvinorin A. Ligand binding causes a conformation change that triggers signaling via guanine nucleotide-binding proteins (G proteins) and modulates the activity of down-stream effectors, such as adenylate cyclase. Signaling leads to the inhibition of adenylate cyclase activity. Inhibits neurotransmitter release by reducing calcium ion currents and increasing potassium ion conductance. Plays a role in the perception of pain. Plays a role in mediating reduced physical activity upon treatment with synthetic opioids. Plays a role in the regulation of salivation in response to synthetic opioids. May play a role in arousal and regulation of autonomic and neuroendocrine functions.[1] [2] [3] [4] ADA1A_HUMAN This alpha-adrenergic receptor mediates its action by association with G proteins that activate a phosphatidylinositol-calcium second messenger system. Its effect is mediated by G(q) and G(11) proteins. Nuclear ADRA1A-ADRA1B heterooligomers regulate phenylephrine(PE)-stimulated ERK signaling in cardiac myocytes.[5] [6] Publication Abstract from PubMedThe alpha(1A-)adrenergic receptor (alpha(1A)AR) belongs to the family of G protein-coupled receptors that respond to adrenaline and noradrenaline. alpha(1A)AR is involved in smooth muscle contraction and cognitive function. Here, we present three cryo-electron microscopy structures of human alpha(1A)AR bound to the endogenous agonist noradrenaline, its selective agonist oxymetazoline, and the antagonist tamsulosin, with resolutions range from 2.9 A to 3.5 A. Our active and inactive alpha(1A)AR structures reveal the activation mechanism and distinct ligand binding modes for noradrenaline compared with other adrenergic receptor subtypes. In addition, we identified a nanobody that preferentially binds to the extracellular vestibule of alpha(1A)AR when bound to the selective agonist oxymetazoline. These results should facilitate the design of more selective therapeutic drugs targeting both orthosteric and allosteric sites in this receptor family. Structural basis of alpha(1A)-adrenergic receptor activation and recognition by an extracellular nanobody.,Toyoda Y, Zhu A, Kong F, Shan S, Zhao J, Wang N, Sun X, Zhang L, Yan C, Kobilka BK, Liu X Nat Commun. 2023 Jun 20;14(1):3655. doi: 10.1038/s41467-023-39310-x. PMID:37339967[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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