1) In the field of biochemistry, an agonist is a substance that binds to a specific receptor and triggers a response in the cell. Agonists often mimic the action of a naturally occurring substance. They can be endogenous (produced within the body, such as hormones or neurotransmitters) or exogenous (introduced from outside the body, such as drugs).
Category/Context: Biochemistry, Pharmacology, Molecular Biology
Related Terms: Antagonist, Receptor, Ligand, Signal Transduction, Full Agonist, Partial Agonist, Inverse Agonist
Examples/Applications: Many drugs act as agonists, binding to specific receptors to elicit a physiological response. For instance, morphine is an agonist for the opioid receptors in the central nervous system.
Student Level: This definition is suitable for undergraduate and graduate students studying biochemistry, molecular biology, and pharmacology.
Etymology/History: The term 'agonist' is derived from the Late Latin word 'agonista', and the Greek word 'agonistes', meaning 'combatant, actor, contestant'.source: