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(Redirected from M5 receptor)
Protein-coding gene in the species Homo sapiens
The human muscarinic acetylcholine receptor M5, encoded by the CHRM5 gene, is a member of the G protein-coupled receptor superfamily of integral membrane proteins. It is coupled to Gq protein. Binding of the endogenousligandacetylcholine to the M5 receptor triggers a number of cellular responses such as adenylate cyclase inhibition, phosphoinositide degradation, and potassium channel modulation. Muscarinic receptors mediate many of the effects of acetylcholine in the central and peripheral nervous system. The clinical implications of this receptor have not been fully explored; however, stimulation of this receptor is known to effectively decrease cyclic AMP levels and downregulate the activity of protein kinase A (PKA).
Ligands
No highly selective agonists or antagonists for the M5 receptor have been discovered as of 2018, but several non-selective muscarinic agonists and antagonists have significant affinity for M5.
The lack of selective M5 receptor ligands is one of the main reasons that the medical community has such a limited understanding of the M5 receptors effects as the possibility that any and/or all effects of non-selective ligands may be due to interactions with other receptors can not be ruled out. Some data may be obtained by observing which effects are common among semi-selective ligands (ex. a ligand of M1 and M5, a ligand of M2 and M5, and a ligand of M3 and M5), but until both a selective agonist and a selective antagonist of the M5 receptor are developed this data must be considered merely theoretical.
Grant MK, El-Fakahany EE (October 2005). "Persistent binding and functional antagonism by xanomeline at the muscarinic M5 receptor". The Journal of Pharmacology and Experimental Therapeutics. 315 (1): 313–9. doi:10.1124/jpet.105.090134. PMID16002459. S2CID11016091.
Further reading
Brann MR, Ellis J, Jørgensen H, Hill-Eubanks D, Jones SV (1993). "Chapter 12: Muscarinic acetylcholine receptor subtypes: Localization and structure/Function". Cholinergic Function and Dysfunction. Progress in Brain Research. Vol. 98. pp. 121–7. doi:10.1016/S0079-6123(08)62388-2. ISBN9780444897176. PMID8248499.
Bonner TI, Young AC, Brann MR, Buckley NJ (July 1988). "Cloning and expression of the human and rat m5 muscarinic acetylcholine receptor genes". Neuron. 1 (5): 403–10. doi:10.1016/0896-6273(88)90190-0. PMID3272174. S2CID833230.
Sato KZ, Fujii T, Watanabe Y, Yamada S, Ando T, Kazuko F, Kawashima K (April 1999). "Diversity of mRNA expression for muscarinic acetylcholine receptor subtypes and neuronal nicotinic acetylcholine receptor subunits in human mononuclear leukocytes and leukemic cell lines". Neuroscience Letters. 266 (1): 17–20. doi:10.1016/S0304-3940(99)00259-1. PMID10336173. S2CID43548155.
Wang H, Han H, Zhang L, Shi H, Schram G, Nattel S, Wang Z (May 2001). "Expression of multiple subtypes of muscarinic receptors and cellular distribution in the human heart". Molecular Pharmacology. 59 (5): 1029–36. doi:10.1124/mol.59.5.1029. PMID11306684.
Buchli R, Ndoye A, Arredondo J, Webber RJ, Grando SA (December 2001). "Identification and characterization of muscarinic acetylcholine receptor subtypes expressed in human skin melanocytes". Molecular and Cellular Biochemistry. 228 (1–2): 57–72. doi:10.1023/A:1013368509855. PMID11855742. S2CID10788646.
Fujii T, Watanabe Y, Inoue T, Kawashima K (April 2003). "Upregulation of mRNA encoding the M5 muscarinic acetylcholine receptor in human T- and B-lymphocytes during immunological responses". Neurochemical Research. 28 (3–4): 423–9. doi:10.1023/A:1022840416292. PMID12675126. S2CID38866084.
De Luca V, Wang H, Squassina A, Wong GW, Yeomans J, Kennedy JL (2004). "Linkage of M5 muscarinic and alpha7-nicotinic receptor genes on 15q13 to schizophrenia". Neuropsychobiology. 50 (2): 124–7. doi:10.1159/000079102. PMID15292665. S2CID29032926.
Qu J, Zhou X, Xie R, Zhang L, Hu D, Li H, Lu F (2006). "The presence of m1 to m5 receptors in human sclera: evidence of the sclera as a potential site of action for muscarinic receptor antagonists". Current Eye Research. 31 (7–8): 587–97. doi:10.1080/02713680600770609. PMID16877267. S2CID3218557.