Supplementary Figure 3: Crystallographic quality control for pregnanolone binding to α5TMD.
From: Structural basis for GABAA receptor potentiation by neurosteroids
(a) SigmaA-weighted 2Fo-Fc (blue, contoured at 2σ) and Fo-Fc (green/red contoured at +3σ/-3σ) electron density maps following refinement in the absence of pregnanolone. (b) The same electron density maps and contour levels following refinement in the presence of pregnanolone. (c) Final model, showing pregnanolone (cyan) bound between the principal (P) and complementary faces (C) of adjacent subunits (PDB chains C and B respectively). Thick dotted lines indicate contacts within hydrogen-bonding distance. Thin dotted lines mark the inter-subunit boundary. (d) Overlay of the five pregnanolone molecules in α5TMD (cyan as in (c), the other four, at equivalent inter-subunit sites, in green). Pregnanolone molecules were overlaid by superposing the complementary chains from each site. Putative hydrogen bond distances between the pregnanolone 3α-hydroxyl and the M1 Gln245 εO range from 2.7-2.8 Å. Putative hydrogen bond distances between the pregnanolone C20 ketone and the Thr309 hydroxyl range from 3.0-3.4 Å.
