Figure 5

Scheme of the 1 + 2 system and its enzymatic first-level reactions. (a) Scheme of the model, with the kinase E₁ and phosphatase E₂ involved in the first-level reactions standing in contrast to the SK activation module. (b) Reactions for the activation and inactivation of the first-level kinase, involving intermediate complexes with E₁ and E₂.