Table 1.

Differences between nAChRs and mAChRs.

Subtypes	FamilyMetabotropic	Structure	SubunitsM1-M5	Agonists	Antagonists
nAChRs	Ionotrophic (ligand-gated ion channel receptors)	Pentameric transmembrane proteins	Neuronal: α2-α10 and β2-β4 Muscle-type: α1, β1, 8, γ (developmental muscle), and ε (mature muscle)	Nicotine PHA543613 Tobacco, nitrosamines Acetycholine NNK	α-Bungarotoxin
mAChRs	G-protein-coupled receptors	Seven-transmembrane proteins	M1-M5	Succinylcholine Muscarine	Atropine