Figure 1.

Basic states for a lobe of CaM in complex with a Ca²⁺ channel (from (Tadross et al., 2008)). In state 1, apoCaM (yellow circle) is bound to the apoCaM site (round pocket). In state 2, apoCaM is a transiently dissociated. In state 3, CaM binds two Ca²⁺ ions (black dots) to become Ca²⁺/CaM (yellow square), which can then bind the Ca²⁺/CaM effector site (square pocket), yielding CDI (state 4).