Cell-surface proteins that bind epinephrine and/or norepinephrine with high affinity and trigger intracellular changes. The two major classes of adrenergic receptors, alpha and beta, were originally discriminated based on their cellular actions but now are distinguished by their relative affinity for characteristic synthetic ligands.
This definition is at least in part based on: Anonymous (2023), Adrenergic receptor (English). Medical Subject Headings. U.S. National Library of Medicine.