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There are 2 glossary search results for:   agonist




Definition:
An agonist is a molecule that binds to a receptor and activates a physiological response similar to that induced by the naturally occurring physiological ligand of the receptor. Therefore, agonist binding to a receptor mimics the action of the natural ligand.

For example, acetylcholine (ACh) is the naturally occurring physiological ligand that activates nicotinic and muscarinic acetylcholine receptors. Nicotine is an agonist of nicotinic ACh receptors (nAChR), and muscarine is an agonist of muscarinic ACh receptors (mAChR).

Related glossary terms/phrases:
Antagonist



Definition:
An antagonist is a molecule that binds to a receptor, however, it does not activate the physiological response induced by the naturally occurring physiological ligand of the receptor. Moreover, once bound to the receptor, an antagonist prevents the physiological ligand from activating the receptor. Therefore, antagonist binding to a receptor prevents or blocks the action of the natural ligand.

For example, acetylcholine (ACh) is the naturally occurring physiological ligand that activates nicotinic and muscarinic acetylcholine receptors. Tubocurarine and succinylcholine are antagonists of the nicotinic ACh receptor (nAChR), and atropine is an antagonist of the muscarinic ACh receptor (mAChR).

Related glossary terms/phrases:
Agonist









Posted: Sunday, March 31, 2013
Last updated: Friday, August 28, 2015