TABLE 2.

Symbols and input parameters

Parameter	Symbol	Value	References
Barbed-end G-ATP on-rate.		11.6 μM−1 s−1	(29)
Barbed-end G-ADP+Pi on-rate.		0	See note below.
Barbed-end G-ADP on-rate.		2.9 μM−1 s−1	(29)
Pointed-end G-ATP on-rate.		1.3 μM−1 s−1	(29)
Pointed-end G-ADP+Pi on-rate.		0	See note below.
Pointed-end G-ADP on-rate.		0.13 μM−1 s−1	Calculated. See note below.
Barbed-end F-ATP off-rate.		1.4 s−1	(29)
Barbed-end F-ADP+Pi off-rate.		1.4 s−1	Equivalence with F-ATP.
Barbed-end F-ADP off-rate.		5.4 s−1	(29)
Pointed-end F-ATP off-rate.		0.8 s−1	(29)
Pointed-end F-ADP+Pi off-rate.		0.8 s−1	Equivalence with F-ATP.
Pointed-end F-ADP off-rate.		0.25 s−1	(29)
Pointed-end Arp2/3 uncapping rate.	kun	0	(24)
Filament branching rate per subunit.		0.01 μ−3 s−1	Simulations fit to data.
F-ATP debranching rate.		0.02 s−1	(46)
F-ADP+Pi debranching rate.		0.04 s−1	(46)
F-ADP debranching rate.		0.2 s−1	(46)
Severing rate per subunit.	ksev	5.0 × 10−4	Simulations fit to data.
Filament annealing rate.		300 μM−1 s−1	(50)
G-ATP hydrolysis rate.		0	(41)
G-ADP+Pi inorganic phosphate release rate.		∞	(41)
F-ATP hydrolysis rate.		0.3 s−1	(51)
F-ADP+Pi inorganic phosphate release rate.		0.002 s−1	(12)
F-ATP hydrolysis range.	khyd	0.02–0.78 s−1	Varied in 0.04 s−1 steps.
F-ADP+Pi inorganic phosphate release range.	kphos	0.002–0.078 s−1	Varied in 0.004 s−1 steps.
Nucleotide exchange rate.	kex	0.01 s−1	(45)

Table of all input parameters used in the stochastic simulation. In accordance with the arguments of Bindschadler et al. (41), we assume that inorganic phosphate is instantly released into solution upon depolymerization of an F-ADP+P_i subunit. The F-ADP pointed-end on-rate is calculated such that the critical concentration at the pointed-end is equal to that of the barbed-end.