Figure 2.

Details of the structure of the anesthetic binding site and the phorbol-binding cleft of the PKCδ C1B subdomain. Carbon atoms are colored gray, oxygen atoms red, nitrogen atoms blue, and sulfur atoms yellow. Thermal ellipsoids at 50% probability represent the water molecules. Waters in the phorbol cleft are omitted for clarity (see Fig. S2 for details). Ligand carbons are cyan. The 2F_o electron density map of the protein (green mesh) is drawn at 1σ cut-off. The equivalent maps around the ligands and water (magenta mesh) are at 1σ, except for CPE where the map is drawn at 0.9σ cut-off. (A) Wild-type C1B containing a water molecule (Water-1) at the anesthetic site. Water-2 and Water-3 form a hydrogen-bond network connecting Thr-242 and Lys-260. (B) CPM bound to C1B. CPM forms a hydrogen bond with Tyr-236. Water-2 and Water-3 form one side of the ligand-binding pocket. The hydroxyl of Ser-240 now adopts two rotamers. (Inset) Thermal ellipsoid representation of CPM. (C) CPM bound to C1B. The hydroxyl of Ser-240 again adopts two rotamers. (Inset) Thermal ellipsoid representation of CPE. (D) Structure of the C1B mutant Tyr-236-Phe. A water molecule occupies the anesthetic binding site in a way very similar to that observed for the wild-type. Neither CPM nor CPE were detected in this mutant (see text). Figures were prepared using Chimera (59).