Table 2.
Model parameters and standard values
| Symbol | Value | Description | Refs. |
|---|---|---|---|
| δ | 2.7 nm | Extension length of polymerizing actin monomer | — |
| D | 6.0 μm2/sec | Cytoplasmic actin monomer diffusion coefficient | 19 |
| [A]TE | 12 μM | Fixed, trailing edge actin monomer concentration | 20 |
| γse | 50 pJ/nm2 | Plasma membrane surface energy coefficient | 18, 21 |
| κb | 80 pN nm | Bending energy coefficient, ≈20 kT | 21 |
| Lp | 10 μm | Persistence length of actin filaments | 22 |
| tlam | 200 nm | Lamellipodial thickness | 20 |
| kon,brb | 12 /μM/sec | On-rate of actin to barbed end ≡ Rpol,b/[A] | 23 |
| koff,brb | 1.4 /sec | Off-rate of actin from barbed end ≡ Rdpol,b | 23 |
| kon,ptd | 0/μM/sec | On-rate of actin to ptd. end, profilin-adj. ≡ Rpol,p/[A] | 24 |
| koff,ptd | 8.0/sec | Off-rate of actin from ptd. end, cofilin-adj. ≡ Rdpol,p | 6 |
| ε | 2.0 δ | LE cap-protection/branch zone (Y) length | 15 |
| Rbr | 0.43/sec | (Total) rate of barbed end branching ≡ kbr [arp2/3] | 18, 20 |
| Rdbr | 0.05/sec | Rate of debranching for any branch point | 25 |
| Rcp | 6.0/sec | Rate of barbed end capping ≡ kon,cp [cp] | 26 |
| Runcp | 0/sec | Uncapping rate for any capped barbed end ≡ koff,cp | 26, 27 |
| Nfb | 200 fil/μm | Free barbed ends per LE width (indirectly spec.) | 20 |
| θbr | 70 deg. | Average branch angle | 4 |
| σbr | 7 deg. | Branch angle SD | 4 |
| Dt | 0.0004 sec | Simulation time step | — |
| fts | 0 (≡ rigid) | Fraction of terminal segment length in fil bending | Text |