Figure 5.

Extended insulin model with receptor degradation (open system). (A) The dose and response differential for the system with synthesis and degradation of membrane-bound receptor R (for reference and perturbed graph) is not defined, since the steady-state coefficient $k_4=0$ (the contained graph is disconnected and therefore does not contain any spanning trees). (B) Tree scheme for a differential system containing synthesis and degradation of the internalized receptor, ${\text{R}}_{\text{i}}$. Graphs without spanning trees are not shown. To see this figure in color, go online.