Peptide Receptors: Agonists, Antagonists and Selectivity

Many peptides communicate by binding to receptors on cell surfaces. An agonist activates a receptor, while an antagonist blocks activation; partial agonists can produce a more limited response under certain conditions. Selectivity describes how strongly a compound interacts with one target compared with others. It is not absolute: receptor behaviour depends on dose, tissue and signalling context. Laboratory assays may measure binding affinity or downstream responses, but these are different endpoints. When evaluating peptide research, distinguish receptor binding from demonstrated clinical benefit. Results in isolated cells do not necessarily predict outcomes in humans.