Fig. 1.

Tertiary structure of ATH. (A) Crystal structure of Ca²⁺-bound ATH. Superposition of the eight Ca²⁺-bound molecules in the asymmetric unit. (B) Solution structure of Ca²⁺-free ATH. An ensemble of the 20 lowest energy structures obtained with CYANA. (C) Surface rendering of the ensemble-average Ca²⁺-bound ATH structure. (D) Surface rendering of the ensemble-average Ca²⁺-free ATH structure, emphasizing the hydrophobic cavity produced by the displacement of the B helix. The views depicted in (C) and (D) were obtained by 90° counterclockwise rotation of the views in (A) and (B) about the vertical axis. This figure and Figs. 4 and 6 were produced with PyMOL ⁶³.