acetylcholine signaling pathway via muscarinic acetylcholine receptor acetylcholine signaling pathway via muscarinic acetylcholine receptors engaging G alphai protein family 2011-04-01T11:01:32Z Acetylcholine signaling via receptor type M2 and M4 primarily engages G alphai protein family resulting in inhibition of adenylate cyclases and reduction of intracellular cAMP. The receptors are expressed in various areas of the brain and the cell membrane of effector tissues. A special feature is their role as autoreceptors at the presynapse of cholinergic neurons. PW:0000856 pathway vpetri