Pathways & interactions
Neurotransmitter-gated ion-channel (IPR006201)
Short name: Neur_channel
Overlapping homologous superfamilies
- Neurotransmitter-gated ion-channel (IPR006201)
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 [PMID: 1721053, PMID: 1846404]. 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 [PMID: 18446614].
- Glycine receptor, an inhibitory chloride ion channel composed of alpha and beta subunits [PMID: 15383648].
- Gamma-aminobutyric acid (GABA) receptor, an inhibitory chloride ion channel; at least four types of subunits (alpha, beta, gamma and delta) are known [PMID: 18760291].
- Serotonin 5HT3 receptor, of which there are seven major types (5HT3-5HT7) [PMID: 10026168].
- Glutamate receptor, an excitatory cation channel of which at least three types have been described (kainate, N-methyl-D-aspartate (NMDA) and quisqualate) [PMID: 15165736].
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 [PMID: 1721053, PMID: 1846404].
The receptors are composed of varying numbers and types of subunit. Each subunit contains a large extracellular N-terminal ligand-binding region; 3 hydrophobic transmembrane domains; a large intracellular region; and a fourth hydrophobic domain. The GABA, acetylcholine, serotonin 5HT3 and glycine receptors share a degree of sequence similarity, but differ from the glutamate receptors - sequences of this family possess 2 Cys residues in the N-terminal domain, which, in nicotinic receptors, form a disulphide bond essential for correct folding of the structure [PMID: 1356407].
This entry includes the subunits of the GABA-A, nicotinic, glycine, glutamate and 5HT3 receptors.