Nicotinic receptors Nomenclature

This problem is recognized by the current nomenclature convention for neuronal nicotinic receptors, which allows referring to a receptor type as, for example, a7, where the asterisk means that a7 may not be the only subunit present. 

The early observation of the different responses elicited by application of muscarine and nicotine suggested two different receptors. Both receptors share the neurotransmitter acetylcholine (ACh), thus both were named cholinergic receptors, but a further nomenclature was followed to distinguish between those preferably affected by muscarine (muscarinic receptors) and those affected by nicotine (nicotinic receptors). 

Lukas, RJ, Changeux, JP, Le Novere, N, Albuquerque, EX, Balfour, DJ, Berg, DK, Bertrand, D, Chiappinelli, VA, Clarke, PB, Collins, AC, Dani, JA, Grady, SR, Kellar, KJ, Lindstrom, JM, Marks, MJ, Quik, M, Taylor, PW and Wonnacott, S (1999) International Union of Pharmacology. XX. Current status of the nomenclature for nicotinic acetylcholine receptors and their subunits. Pharmacol. Rev. 51(2) 397 01. 

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