Kinetic schemes and parameters used in the model.

<p>A: Binding of Ca²⁺ with CaM. The backward rate constants of Ca²⁺ with CaM are changed in the presence of CNG channels (red). B: Binding of cAMP (gray) with the CNG channels. C: The model of interaction between CNG channels and Ca²⁺/CaM considered that CNG channels can associate to CaM with less than four Ca²⁺. However, the interaction between CNG channels and CaM with one or two Ca²⁺ has a weaker affinity than the interaction between CNG channels and CaM with three or four Ca²⁺. Ca²⁺/CaM can bind to open and closed CNG channels with the same affinities. D: Binding of Ca²⁺ to CAC channels.