Alpha subunit of the heteropentameric ligand-gated chloride channel gated by gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter in the brain (PubMed:10449790, PubMed:29961870, PubMed:31032849). 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 interfaces (By similarity). When activated by GABA, GABAARs selectively allow the flow of chloride anions across the cell membrane down their electrochemical gradient (PubMed:10449790). Chloride influx into the postsynaptic neuron following GABAAR opening decreases the neuron ability to generate a new action potential, thereby reducing nerve transmission (By similarity). The alpha-2 subunit exhibits synaptogenic activity together with beta-2 and very little to no activity together with beta-3, the gamma-2 subunit being necessary but not sufficient to induce rapid synaptic contacts formation (By similarity). {ECO:0000250|UniProtKB:P10063, ECO:0000250|UniProtKB:P14867, ECO:0000250|UniProtKB:P26048, ECO:0000269|PubMed:10449790, ECO:0000269|PubMed:29961870, ECO:0000269|PubMed:31032849}. This is the function of Ensembl gene identifier ENSG00000151834 (GABRA2, gamma-aminobutyric acid type A receptor subunit alpha2).