TABLE 1:

Model parameters.

Parameter	Value/units	Definition	Source
L	36–138 nm	Local average lengths of actin filaments	Estimated in Results
N	12–46	Local numbers of subunits in a filament
t0	13 s	Parameter used in modeling fc(t)
τ	0.66 s	Parameter used in modeling fc(t)
ηA	602 μm–3/μM	Conversion factor
μ	0.4 nm/(s · pN)	Mobility coefficient	Defined in Model
kactive	Pa/(μM)2	Active stress coefficient	Computed in Model
kvisc	Pa⋅s/μM	Shear viscosity coefficient	Estimated in Model
ρmax	20.15 × 103nA μM	Maximum actin density	Defined in Model
nmax	6500	Maximum number of actin subunits in a patch	Berro et al., 2010
RArp2/3	0.035–0.06	Molar Arp2/3 complex-to-actin ratio
G0	21.6 μM	Concentration of actin monomers
fstall	10.5 pN	Actin polymerization stalling force	Estimated in Results
εmax	6.9 kBT	Maximum energy stored in the patch per subunit	Estimated in Results
E	1 GPa	Young’s modulus of the actin filament	Broedersz and MacKintosh, 2014
I	πa4/4 nm4	Rotational inertia of the filament
a	3.5 nm	Radius of the filament cross-section
δ	2.7 nm	Radius of actin subunit
WASp0	259.6 μm–2	Surface density of NPFs	Based on Berro et al., 2010
Arp0	1.3 μM	Concentration of Arp2/3 complex	Berro et al., 2010
C0	0.8 μM	Concentration of capping protein
COF0	40 μM	Concentration of cofilin