Characterization of novel benzodiazepine ligands in Spodotera frugiperda (Sf-9) insect cells.

The goals of the present work were to characterize the binding profile of nine benzodiazepine ligands in Spodotera frugiperda (Sf-9) insect cells expressing specific gamma aminobutyric acid (A) (GABA(A)) receptor subunit combinations and compare the affinities to those for the receptors in the rat cerebellum. Three recombinant baculovirus constructs, each harboring a different GABA(A) receptor subunit, were introduced into insect cells by simultaneous infection. Saturation and competition binding assays were carried out in membranes from Sf-9 cells infected with either alpha1beta2gamma2 or alpha6beta2gamma2 subunit combinations. The affinities of the ligands to the alpha1beta2gamma2 or alpha6beta2gamma2 receptors expressed in Sf-9 cells were similar to the affinities previously determined for the alpha1 or alpha6 subunit-containing GABA(A) receptors in the rat cerebellum, respectively, thus confirming the previously assigned receptor types in the cerebellum.