Beta-1 adrenergic receptor and Beta-2 adrenergic receptor (β1-AR, ADRB1, β2-AR, ADRB2)

Beta-1 adrenergic receptor and Beta-2 adrenergic receptor are homologous G protein-coupled receptors located on cell membranes, sharing about 50% amino acid identity and featuring seven transmembrane domains. Beta-1 adrenergic receptors are predominantly found in the heart and mediate positive chronotropic and inotropic effects in response to catecholamines, while beta-2 adrenergic receptors are expressed mainly in airway and vascular smooth muscle, where activation leads to muscle relaxation and bronchodilation. Both play foundational roles in the regulation of cardiovascular and respiratory physiology, are key targets for agonist and antagonist drugs, and have distinct disease relevance, pharmacological profiles, and therapeutic challenges.

Other names

Beta-1 receptorβ1-ARADRB1Beta-2 receptorβ2-ARADRB2

Agonists: Bind receptor → activate adenylyl cyclase via Gs protein → increase cAMP → physiological effect (cardiac stimulation for β1; smooth muscle relaxation for β2). Antagonists (“beta-blockers”): Block receptor → inhibit catecholamine binding → decrease cAMP → reduced physiological effect (slower heart rate and contractility for β1; less smooth muscle relaxation for β2).