Muscarinic Acetylcholine Receptor M2 (M2 mAChR)

The Muscarinic Acetylcholine Receptor M2 (M2 mAChR) is a G protein-coupled receptor that primarily couples to Gi/o proteins. Upon activation by acetylcholine, it inhibits adenylyl cyclase activity, reducing cAMP levels, and activates G protein-coupled inwardly rectifying potassium channels, particularly in the heart, leading to hyperpolarization and decreased excitability. It plays a key role in regulating cardiac rate, airway smooth muscle tone, and has been implicated in central nervous system functions. The high degree of conservation at the orthosteric binding pocket complicates the development of highly subtype-selective ligands.

Other names

Cholinergic receptor, muscarinic 2

Agonists bind to the orthosteric site, activating Gi/o proteins, which inhibits adenylyl cyclase and activates G protein-coupled inwardly rectifying potassium channels. Antagonists block the orthosteric site, preventing acetylcholine binding and downstream signaling.