Figure 4

Structure of the Excalibur domain determined by NMR.

(A) Superposition of the 20 low energy conformers of the Excalibur domain determined by NMR. Ca²⁺ is depicted in red sphere. (B) Ribbon representation of one Excalibur conformer showing its main structural features. (C) Ca²⁺-binding loop architecture and localization of the disulfide bridge. (D) Backbone superimposition between the Ca²⁺-binding loop of the Excalibur domain and calmodulin (PDB code 1CLL) with a rmsd_backbone = 0.69 Å.