The nicotinic acetylcholine receptors (nAChRs) are members of a superfamily of ligand-gated ion channels that mediate fast signal transmission at synapses. The nAChRs are thought to be hetero-pentamers composed of homologous subunits. The proposed structure for each subunit is a conserved N-terminal extracellular domain followed by three conserved transmembrane domains， a variable cytoplasmic loop， a fourth conserved transmembrane domain， and a short C-terminal extracellular region. The protein encoded by this gene forms a homo-oligomeric channel， displays marked permeability to calcium ions and is a major component of brain nicotinic receptors that are blocked by， and highly sensitive to， alpha-bungarotoxin. Once this receptor binds acetylcholine， it undergoes an extensive change in conformation that affects all subunits and leads to opening of an ion-conducting channel across the plasma membrane. This gene is located in a region identified as a major susceptibility locus for juvenile myoclonic