Characterization of recombinant GABAA receptors produced in transfected cells from murine alpha 1, beta 1, and gamma 2 subunit cDNAs.

In order to explore the structural basis of GABAA receptor function, we have expressed murine alpha 1, beta 1, and gamma 2 subunit cDNAs by transient transfection of human 293 cells. Expression of GABAA receptors was measured by ligand binding assay and by electrophysiological analysis. As in other species, expression of the alpha 1 and beta 1 subunits produced a receptor that was insensitive to modulation by benzodiazepines as measured by electrophysiological analysis; however, a small number of flunitrazepam binding sites were detectable. The coexpression of the gamma 2 subunit was found to be essential for this modulation, and also resulted in a dramatic (14-fold) increase in the number of binding sites for flunitrazepam. On the coexpression of all 3 subunit cDNAs, a receptor was produced that exhibited a similar number of binding sites for flunitrazepam and muscimol.