Peptides are tiny protein messengers that cells use to send signals and trigger...

https://wiki-aero.win/index.php/What_Is_an_Antagonist_in_Receptor_Signaling%3F_A_Close_Look_at_Biological_Communication

Peptides are tiny protein messengers that cells use to send signals and trigger responses. In the lab, researchers study how peptides latch onto specific receptors to understand selectivity and activate signaling pathways