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QuickView for Neurotransmitter-gated ion-channel (biogroup)
- 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.The receptors are composed of varying numbers and types of subunit. Eachsubunit contains a large extracellular N-terminal ligand-binding region;3 hydrophobic transmembrane domains; a large intracellular region; and afourth hydrophobic domain. The GABA, acetylcholine, serotonin 5HT3and glycine receptors share a degree of sequence similarity, but differfrom the glutamate receptors - sequences of this family possess 2 Cysresidues in the N-terminal domain, which, in nicotinic receptors, form adisulphide bond essential for correct folding of the structure.This entry includes the subunits of the GABA-A, nicotinic, glycine, glutamate and 5HT3 receptors.
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