Figure 2.

Overall structure of CsCyp in complex with CsA. A, Cartoon depicting the 3D structure of CsCyp (gray) showing the typical Cyp fold comprising eight β-strands that form a β-barrel closed by two α-helices. CsA is shown with light blue sticks. The divergent loop (pink) and conserved Glu-83 (green) are shown. B, A 40° rotated image showing the invariable Cys residues Cys-40 and Cys-168 (cyan and blue, respectively) and their thiol groups 5.4 Å apart (dashed yellow line). C, Detailed view of the hydrogen bond network between the side chain of Glu-83 and Lys-48 and Ser-49 of the divergent loop.