Muscarinic acetylcholine receptors are G protein-coupled receptors. M1, M3, M5 receptors couple to G proteins of the Gq/11 family, which activate phospholipase C. M2 and M4 receptors couple to Gi/o-type G proteins that inhibit adenylyl cyclase activity. Muscarinic receptors control many effects of acetylcholine in the central and peripheral nervous system. M1 receptor is known to mediate slow EPSP at the ganglion in the postganglionic nerve, and it is also found in exocrine glands and in the CNS. M1 receptor is thought to be implicated in Alzheimer′s disease.