Alpha subunit of the heteropentameric ligand-gated chloride channel gated by gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter in the brain (PubMed:14993607, PubMed:29961870, PubMed:30140029, PubMed:31056671). GABA-gated chloride channels, also named GABA(A) receptors (GABAAR), consist of five subunits arranged around a central pore and contain GABA active binding site(s) located at the alpha and beta subunit interface(s) (PubMed:30140029). When activated by GABA, GABAARs selectively allow the flow of chloride anions across the cell membrane down their electrochemical gradient (PubMed:14993607, PubMed:30140029). GABAARs containing alpha-5/GABRA5 subunits are mainly extrasynaptic and contribute to the tonic GABAergic inhibition in the hippocampus (By similarity). Extrasynaptic alpha-5- containing GABAARs in CA1 pyramidal neurons play a role in learning and memory processes (By similarity). {ECO:0000250|UniProtKB:Q8BHJ7, ECO:0000269|PubMed:14993607, ECO:0000269|PubMed:29961870, ECO:0000269|PubMed:30140029, ECO:0000269|PubMed:31056671}. This is the function of Ensembl gene identifier ENSG00000186297 (GABRA5, gamma-aminobutyric acid type A receptor subunit alpha5).