Figure 9.

Alignment of Ca²⁺-saturated and Ca²⁺-depleted average structures of cTnC. Calcium ion locations are shown as large spheres colored according to their appropriate state. Note the lack of a calcium ion in the N-lobe in the Ca²⁺-depleted state. There is significant change in the conformation of the N-lobe while the C-lobe remains mostly unchanged. The Ca²⁺ ion positions bound to the C-lobe in the two states are virtually superimposed. Binding sites I and II as well as the linker between them are significantly altered as a result of removing Ca²⁺. This corresponds to the changes in RMSF that we see in Figure 7.