extracellular domain (ECD) of anionic Cys-loop neurotransmitter-gated ion channels
This family contains the extracellular domain (ECD) of anionic Cys-loop neurotransmitter-gated ion channels which include type-A gamma-aminobutyric acid receptor (GABAAR), glycine receptor (GlyR), invertebrate glutamate-gated chloride channel (GluCl), and histimine-gated chloride channel (HisCl). These neurotransmitter receptors directly mediate chloride permeability and constitute one half of the Cys-loop receptor family. Receptors in this family are composed of five either identical or homologous subunits, which generate diversity in functional profiles and pharmacological preferences. GABAAR and GlyR, both mediate fast inhibitory synaptic transmission. Cl- ions are selectively conducted through the GABAAR receptor pore, resulting in hyperpolarization of the neuron. GluCl channels are found only in protostomia, but are closely related to mammalian glycine receptors (GlyRs). They have several roles in these invertebrates, including controlling locomotion and feeding, and mediating sensory inputs into behavior. Ligand-gated chloride channels are critical not only for maintaining appropriate neuronal activity, but have long been important therapeutic targets: benzodiazepines, barbiturates, some intravenous and volatile anaesthetics, alcohol, strychnine, picrotoxin, and ivermectin all derive their biological activity from acting on this inhibitory half of the Cys-loop receptor family. Many of the therapeutically useful compounds acting at Cys-loop receptors target an allosteric site. The sites in Cys-loop receptors at which these allosteric ligands bind and their structure-based mechanisms of action are largely unresolved.
Structure:4COF: Homo sapiens extracellular domain of gamma-aminobutyric acid A receptor (GABAAR) interacts with adjacent subunits, and forms a pentamer; contacts at 4.0A
Structure:3RHW: Caenorhabditis elegans extracellular domain of glutamate-gated chloride channel (GluCl) interacts with adjacent subunits, and forms a pentamer; contacts at 4.0A
Jiyao W et al.(2023). "The conserved domain database in 2023.",