Receptor Agonist
A molecule that binds to a specific receptor and activates it, triggering a biological response. Many therapeutic peptides function as receptor agonists, mimicking the action of natural hormones. GLP-1 receptor agonists and GnRH agonists are among the most widely prescribed peptide drug classes.
Technical Context
Agonists produce effects by binding to the same site as the natural ligand (orthosteric agonists) or at a different site that enhances receptor activity (allosteric agonists). The degree of activation varies: full agonists produce maximal receptor response, while partial agonists produce submaximal response even at full receptor occupancy. In peptide therapeutics, GLP-1 receptor agonists (semaglutide, liraglutide, dulaglutide, exenatide, lixisenatide, tirzepatide) are the most commercially significant class. Other examples include GnRH agonists (goserelin, leuprolide), melanocortin agonists (bremelanotide, setmelanotide, afamelanotide), GHRH agonists (tesamorelin), and vasopressin/oxytocin receptor agonists.