extracellular domain of gamma-aminobutyric acid receptor subunit alpha-4 (GABAAR-A4 or GABRA4)
This family contains extracellular domain of gamma-aminobutyric acid receptor subunit alpha-4 (GABAAR-A4), a protein that is encoded by the GABRA4 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-4 subunit forms heteropentamers with other GABAAR subunits, most broadly expressed as combination of alpha2alpha4beta1gamma1, all four subunits existing on the same gene cluster. Alpha-4 is involved in the etiology of autism and eventually increases autism risk through interaction with the beta-1 (GABRB1) subunit. Polymorphism in GABRA4 may trigger migraine by ethanol, while another is associated to faster reaction times and with lower ethanol effects. A rare variant in GABRA4 may have modest physiological effect in autism spectrum disorder etiology.
Jiyao W et al.(2023). "The conserved domain database in 2023.",