Table 2.

Summary of variables used in the model

Variable	Description
Fundamental geometrical entities
ri	Radius of annular region i
li	Arc length of annular region i
P	Point on which the annuli are centered
Derived geometrical variables
hi	Height contributed by annular region i
di	Distance of annular region i from tip
si	Arc length from P to annular region i
Ai	Surface area of one face of annular region i
Protein densities
Ei	Exocyst density in annular region i
Si	Synthase density in annular region i
Parameters
σ	Standard deviation of Gaussian distribution for E
ε	Parameter linking exocyst density to rate of synthase exocytosis
γ	Parameter linking synthase density to rate of surface area growth
sendo	Arc length from tip at which endocytosis starts (model using equation 3b)
ϕ	Fraction of synthase that undergoes endocytosis during one time step (model using equation 3b)
δt	Time step for updating the variables; acts simply to scale ε, γ, and ϕ and is therefore implicitly set to 1 in calculations