[5] This receptor is found mediating slow EPSP at the ganglion in the postganglionic nerve,[6] is common in exocrine glands and in the CNS.

[7][8] It is predominantly found bound to G proteins of class Gq[9][10] that use upregulation of phospholipase C and, therefore, inositol trisphosphate and intracellular calcium as a signalling pathway.

A structural but not sequential homolog of the human M1 receptor has been reported in Acanthamoeba castellanii[15] and Naegleria fowleri.

[16] Antagonists of human M1 receptors (e.g. atropine, diphenhydramine) have been shown to exert anti-proliferative effects on these pathogens.

[9] This article incorporates text from the United States National Library of Medicine, which is in the public domain.