Figure 5. TANGO1 widens the parameter space at which membrane tension regulation can trigger the growth of a stable incomplete carrier.

(A) Phase diagram obtained with Model B displaying the optimal shape parameter as a function of the COPII coat binding energy, ${\mathit{\mu }}_{\mathit{c}}^0$, and of the membrane tension, $\mathit{\sigma }$. Different shapes can be identified, from flat uncoated membranes, ${\mathit{\eta }}^{\mathit{*}}=0$, to incomplete coated buds, ${\mathit{\eta }}^{\mathit{*}}<1/2$, and to large transport intermediates, ${\mathit{\eta }}^{\mathit{*}}>1$. Unless otherwise specified, parameters used for all the calculations are listed in Appendix 2—table 1. ER and Golgi membrane tensions are marked by yellow dashed lines. (B) Shape factor (color code) and final state (symbol) obtained with Model A as a function of membrane tension ($\mathit{\sigma }$) and COPII self-interaction (${\mathit{\chi }}_{\mathit{c}}$). (i) Inert TANGO1 but functional COPII. (ii) Functional TANGO1 and COPII. Each symbol represents the final state of a dynamic simulation, while iso-contours and colors are interpolated from the values at each symbol. (C) Snapshots of final states obtained for functional TANGO1 at ${\displaystyle \mathit{\sigma }=0.006k_{B}T/n{m}^2}$ as indicated in panel (B). Note that (i) and (ii) reached local equilibrium states.