Members of the ligand-gated ion channel receptor family are characterized by their fast transmitting response to neurotransmitters. Two important members of this family are the nicotinic acetylcholine and glutamate receptors, both of which are composed of five homologous subunits forming a transmembrane aqueous pore. These transmembrane receptors change conformation in response to their cognate neurotransmitter. Nicotinic acetylcholine receptors (AChRs) are found at the postsynaptic membrane of the neuromuscular junction and bind acetylcholine molecules, allowing ions to move through the pore. AChR alpha 6, also designated cholinergic nicotinic receptor alpha polypeptide 6, is a neuronal acetylcholine receptor protein expressed in respiratory mucosa. AChR alpha 6 is also selectively expressed on dopaminergic terminals, where it complexes with AChR Beta 2 and AChR alpha 4.