Appendix 1—table 1. System’s parameters.

$K_{\mathrm{b}}$	Budding rate per patches of membrane in a compartment
$K_{\mathrm{m}}$	biochemical conversion rate for each patch of membrane (cis→medial→trans)
$K_{\mathrm{f}}$	Maximum fusion rate between two compartments
$J$	Injection rate of cis-vesicles from the ER
$k_{\mathrm{b}}$	Budding rate normalized by the fusion rate ($K_{\mathrm{b}}/K_{\mathrm{f}}$)
$k_{\mathrm{m}}$	biochemical conversion rate normalized by the fusion rate ($K_{\mathrm{m}}/K_{\mathrm{f}}$)
$j$	Injection rate normalized by the fusion rate ($J/K_{\mathrm{f}}$)
$\alpha$	Fraction of active species (driving homotypic fusion) in the ER (cis) or the TGN (trans)
${\alpha }_i$	When different between boundaries, $\alpha$ in the boundary $i$ ($i$ equals ER or TGN)