FIGURE 2.

Structure of the RORγt LBD in complex with digoxin. A, chemical structure of digoxin with numbering. B, σA-weighted 2Fo-Fc electron density map shown as a dark blue mesh around digoxin. The protein is drawn as a stick model and digoxin is depicted as a ball-and-stick model. Contour level is 1.2 σ. C, schematic representation of the RORγt LBD (dark blue) with digoxin. The secondary structure assignment, and the N and C termini are labeled. Bound digoxin is depicted as a CPK model with carbon atoms in cyan and oxygen atoms in red. D, superposition of two RORγt LBDs in the asymmetric unit of the crystal. The protein is drawn as a cartoon model with molecule A and molecule B colored in pink and dark blue. Digoxin is shown as a stick model with carbons in orange for monomer A and carbons in cyan for monomer B. The structures of a lactone group, central steroidal core and digitoxose X of digoxin are superposed well. The conformation of digitoxose Y and Z are significantly different.