Fig. 4
From: Structural basis of neurosteroid anesthetic action on GABAA receptors
Alphaxalone binding mode in the α1GABAAR chimera. a 2D chemical structure of alphaxalone with rings and carbon atoms labeled according to the IUPAC standard for steroids. b Crystal structure of alphaxalone (cyan) bound to a pocket lined by residues in the transmembrane domain from the principal (yellow) and complementary (white) subunits of the α1GABAAR chimera. Alphaxalone is surrounded by the 2FO–FC electron density map contoured at 1 σ (blue mesh). Three residues in close contact with alphaxalone are highlighted. Functional validation of the alphaxalone-binding site was performed by c activation of Xenopus oocytes expressing WT (solid circles), T306A (open circles), Q242L (solid squares) and W246L (open squares) α1GABAAR chimeras by propylamine (PPA) with EC50 = 20 ± 1, 23 ± 2, 39 ± 3, and 3300 ± 300 μM, respectively; d alphaxalone (0.1 μM) potentiation at the EC10 concentration of PPA; e alphaxalone (3 μM) activation normalized to EC100 PPA activation for each construct. Error bars represent SEM (n ≥ 3 oocytes). Statistical significance was assessed by one-way ANOVA followed by Fisher’s LSD post-hoc test. Asterisks indicate statistical difference from WT at p < 0.001 (***) and p < 0.05 (*)
