Figure 4. Superimposition of the FK1 domains of FKBP51 and FKBP52.

The FKBP51 X-ray structure from PDB code 3O5P [28] is illustrated in yellow, whereas molecule A from PDB code 4LAV [33] for FKBP52 is shown in grey. All heavy atoms are illustrated for the β₄–β₅ loop extending from Glu¹¹⁰ to Leu¹²⁸. Substantial deviations in backbone geometry are only apparent for the β₃ bulge (Ser⁷⁰–Lys⁷⁶) and the tip of the β₄–β₅ loop.