Figure 5

Single parameter bifurcation diagrams. In these diagrams, obtained using AUTO [14], we plot the steady state activity of internal cAMP (x₅) as a function of four individual parameters (k₁, k₂, k₈ and k₁₀). In the diagrams, a stable steady state is represented by solid line; an unstable steady state is represented by dashed line; and a stable limit cycle is represented by a pair of solid circles with the upper indicating the maximum value of amplitude and the lower indicating the minimum value of amplitude. The transition from stable steady state to stable limit cycle or vice versa is called a Hopf bifurcation, which is indicated by a solid square in the plot. This type of bifurcation is caused by the appearance of a pair of pure imaginary eigenvalues of the Jacobian matrix of non-linear system. A star on the axis indicates the nominal value of each parameter.