The beta-adrenergic receptors ( beta-AR ) are G protein-coupled receptors activated by epinephrine and norepinephrine and are involved in a variety of their physiological functions .
O B-GeneOrGeneProduct I-GeneOrGeneProduct O B-GeneOrGeneProduct O O O O O O O B-ChemicalEntity O B-ChemicalEntity O O O O O O O O O O O