extracellular domain of gamma-aminobutyric acid receptor subunit beta-2 (GABAAR-B2 or GABRB2)
This family contains extracellular domain (ECD) of gamma-aminobutyric acid receptor beta-2 subunit, a protein that is encoded by the GABRB2 gene. 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 beta-2 subunit forms heteropentamers with other GABAAR subunits, with alpha1-beta2-gamma2 subtype being the most prevalent isoform (approximately 50%-60% of all GABAARs), and are expressed in almost all regions of the brain. It also assembles less abundantly as alpha4beta2/3delta and alpha6beta2/3delta. Mutations or genetic variations of the genes encoding the GABRB2 and GABRB3 have been associated with human epilepsy, both with and without febrile seizures. Mutations in GABRB2, and GABRB3 have been associated with infantile spasms and Lennox-Gastaut syndrome. A de novo missense mutation of GABRB2 causes early myoclonic encephalopathy, a disease with a devastating prognosis, characterized by neonatal onset of seizures. Another de novo heterozygous missense variant in exon 4 of GABRB2 is associated with intellectual disability and epilepsy. GABRB2 plays important tumorigenic functions and acts as a novel oncogene in papillary thyroid carcinoma (PTC).
Jiyao W et al.(2023). "The conserved domain database in 2023.",