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Publication Abstract from PubMed

Beta adrenergic receptors (betaARs) mediate physiologic responses to the catecholamines epinephrine and norepinephrine released by the sympathetic nervous system. While the hormone epinephrine binds beta1AR and beta2AR with similar affinity, the smaller neurotransmitter norepinephrine is approximately tenfold selective for the beta1AR. To understand the structural basis for this physiologically important selectivity, we solved the crystal structures of the human beta1AR bound to an antagonist carazolol and different agonists including norepinephrine, epinephrine and BI-167107. Structural comparison revealed that the catecholamine-binding pockets are identical between beta1AR and beta2AR, but the extracellular vestibules have different shapes and electrostatic properties. Metadynamics simulations and mutagenesis studies revealed that these differences influence the path norepinephrine takes to the orthosteric pocket and contribute to the different association rates and thus different affinities.

Binding pathway determines norepinephrine selectivity for the human beta1AR over beta2AR.,Xu X, Kaindl J, Clark MJ, Hubner H, Hirata K, Sunahara RK, Gmeiner P, Kobilka BK, Liu X Cell Res. 2020 Oct 22. pii: 10.1038/s41422-020-00424-2. doi:, 10.1038/s41422-020-00424-2. PMID:33093660^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.