Figure 4. The predicted impacts of uncoupling the coupled switches.

• A, B
  Fractional activations of mGEF vs. active Arf1 (mG*) for the single switch (A; mG alone) and coupled switches (B; mG and tG). We perform stochastic simulations in the presence of noise in EGF (see Materials and Methods for details). The mean and the standard deviation (SD) of species are evaluated at steady states based on 1,000 repeated independent simulations of ODEs in the presence of noise. $\overline{\mathit{\text{mGEF}}}$ denotes the mean of mGEF; the shading shows the SD. The dimensionless EGF concentrations in the simulations are obtained through normalization, that is, dividing the EGF concentration by 217.4 nM (=50 nM/0.23). In all simulations, noise is introduced only in stimulus (i.e., EGF).
• C, D
  A comparative analysis of the Golgi‐localized Arf1 (mG) connectome with/without coupling to GIV (tGEF) and Gi (tGTPase). Workflow (C) shows how the list of Golgi‐localized Arf1 and GIV interacting proteins (Appendix Fig S1 and Dataset EV1) were used as “seeds” to construct a PPI network from the STRING database to fetch the linking nodes to connect the seed proteins. The network was then perturbed by in silico deletion of GIV, followed by a topological analysis of how such perturbation impacts the shortest paths associated with Arf1 to all other nodes in the network (see Materials and Methods). A network representation (D) using the ClueGo algorithm of the cellular processes associated with the end proteins that were most frequently encountered in the most impacted shortest paths associated with Arf1 (listed in Appendix Fig S2 E). The deleted or newly added shortest paths were only considered using the differential network approach (see Materials and Methods). The key in the lower left corner displays the color code of various overarching themes encountered in the network.