Structural basis of agonist specificity of α<sub>1A</sub>-adrenergic receptor.

Su, Minfei; Wang, Jinan; Xiang, Guoqing; Do, Hung Nguyen; Levitz, Joshua; Miao, Yinglong; Huang, Xin-Yun · Nat Commun · 2023

basic_science · Level V

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Abstract

α<sub>1</sub>-adrenergic receptors (α<sub>1</sub>-ARs) play critical roles in the cardiovascular and nervous systems where they regulate blood pressure, cognition, and metabolism. However, the lack of specific agonists for all α<sub>1</sub> subtypes has limited our understanding of the physiological roles of different α<sub>1</sub>-AR subtypes, and led to the stagnancy in agonist-based drug development for these receptors. Here we report cryo-EM structures of α<sub>1A</sub>-AR in complex with heterotrimeric G-proteins and either the endogenous common agonist epinephrine or the α<sub>1A</sub>-AR-specific synthetic agonist A61603. These structures provide molecular insights into the mechanisms underlying the discrimination between α<sub>1A</sub>-AR and α<sub>1B</sub>-AR by A61603. Guided by the structures and corresponding molecular dynamics simulations, we engineer α<sub>1A</sub>-AR mutants that are not responsive to A61603, and α<sub>1B</sub>-AR mutants that can be potently activated by A61603. Together, these findings advance our understanding of the agonist specificity for α<sub>1</sub>-ARs at the molecular level, opening the possibility of rational design of subtype-specific agonists.

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