Pharmacology
Antagonist
An antagonist is a molecule that binds to a receptor but does not activate it, blocking the action of the natural ligand or agonist.
Detailed Explanation
Antagonists have affinity for a receptor but no efficacy. They compete with agonists for binding sites (competitive antagonists) or bind to different sites to reduce agonist effect (non-competitive antagonists). In peptide research, ACE-031 acts as a functional antagonist by acting as a decoy receptor for myostatin, preventing it from binding its native receptor.