extracellular domain of gamma-aminobutyric acid receptor subunit alpha-5 (GABAAR-A5 or GABRA5)
This family contains extracellular domain of gamma-aminobutyric acid receptor subunit alpha-5 (GABAAR-A5), a protein that is encoded by the GABRA5 gene in humans, with biased expression in the brain and heart. GABAAR is an anionic channel, mediating fast inhibitory synaptic transmission. Upon gamma-aminobutyric acid (GABA) binding to the ligand binding site on the ECD, Cl- ions are selectively conducted through the GABAAR pore, resulting in hyperpolarization of the neuron. GABAAR is the principal mediator of rapid inhibitory synaptic transmission in the human brain. A decline in GABAAR signaling triggers hyperactive neurological disorders such as insomnia, anxiety, and epilepsy. The alpha-5 subunit forms heteropentamers with other GABAAR subunits, most broadly expressed as alpha5-beta-gamma2, and probably alpha5-beta3-gamma2, predominantly expressed in the hippocampus and localized extrasynaptically. These receptors have been demonstrated to play an important modulatory role in learning and memory processes, thus making them suitable targets for pharmacological intervention. Studies show that alpha5-containing GABAARs play an important part in tonic inhibition in hippocampal pyramidal neurons, and that these can also contribute to synaptic inhibition. Studies strongly suggest that amnesia is primarily mediated by alpha5-beta-gamma2. Polymorphisms in GABRA5 (and GABRA3) are linked to the susceptibility to panic disorder. A genetic association also exists between GABRA5 and bipolar affective disorder.
Jiyao W et al.(2023). "The conserved domain database in 2023.",