Protein Domain : Nicotinic acetylcholine receptor IPR002394

Type	Family
Description	Neurotransmitter ligand-gated ion channels are transmembrane receptor-ion channel complexes that open transiently upon binding of specific ligands, allowing rapid transmission of signals at chemical synapses [ , ]. Five of these ion channel receptor families have been shown to form a sequence-related superfamily:Nicotinic acetylcholine receptor (AchR), an excitatory cation channel in vertebrates and invertebrates; in vertebrate motor endplates it is composed of alpha, beta, gamma and delta/epsilon subunits; in neurons it is composed of alpha and non-alpha (or beta) subunits [].Glycine receptor, an inhibitory chloride ion channel composed of alpha and beta subunits [ ].Gamma-aminobutyric acid (GABA) receptor, an inhibitory chloride ion channel; at least four types of subunits (alpha, beta, gamma and delta) are known [ ].Serotonin 5HT3 receptor, of which there are seven major types (5HT3-5HT7) [ ].Glutamate receptor, an excitatory cation channel of which at least three types have been described (kainate, N-methyl-D-aspartate (NMDA) and quisqualate) [ ].These receptors possess a pentameric structure (made up of varying subunits), surrounding a central pore. All known sequences of subunits from neurotransmitter-gated ion-channels are structurally related. They are composed of a large extracellular glycosylated N-terminal ligand-binding domain, followed by three hydrophobic transmembrane regions which form the ionic channel, followed by an intracellular region of variable length. A fourth hydrophobic region is found at the C-terminal of the sequence [ , ].Nicotinic acetylcholine receptors are ligand-gated ion channels that mediate signal transduction at the post-synaptic membrane of cholinergic synapses, such as the neuromuscular junction [ ]. They belong to a family of neurotransmitter-gated receptors, including glycine, gamma-aminobutyric-acid (GABA), serotonin 5HT3 receptors. These are oligomeric transmembrane (TM) complexes (pentamers of 2 alpha and 1 beta, 1 gamma and 1 delta subunit) that contain a central channel, which transiently opens upon binding of a specific neurotransmitters. Their sequences are related and share the same topology: each has an extracellular, glycosylated N-terminal ligand-binding domain; 3 hydrophobic TM regions, which form the channel; a hydrophilic cytoplasmic domain; followed by a fourth putative TM region []. The nicotinic receptor ligand binding domain is a specialised pocket of aromatic and hydrophobic residues formed at interfaces between protein subunits that changes conformation to convert agonist binding into gating of an intrinsic ion channel []. The expression of acetylcholine receptors is activated during muscle differentiation and upon denervation of adult muscle []. Receptor function is regulated by phosphorylation and dephosphorylation by kinases and phosphatases present in the post-synaptic membranes []. Most of the phosphorylation sites are located in the major intracellular loop between the third and fourth TM regions and are closely spaced.
Short Name	Nicotinic_acetylcholine_rcpt