TABLE 2.
Model parameters
| Symbol | Meaning | Value | References |
|---|---|---|---|
| d | Diameter of filopodium | ∼0.2 μm | (25) |
| N | No. of filaments in filopodial bundle | ∼10–30 | (12,25) |
| F | Membrane resistance force | ∼20 (10–50) pN | (26–28) |
| kBT | Thermal energy | 4.1 pN × nm | (26) |
| Lp | F-actin persistence length | 10 (1–20) μm | (29,30) |
| B | Membrane bending resistance | 50 kBT | References in Peskin et al. (26) |
| δ | Half-size of actin monomer | ≈2.7 nm | References in Peskin et al. (26) |
| D | Effective G-actin diffusion coefficient | ∼5 μm2/s | (55) |
| a0 | G-actin concentration at the leading edge | ∼10 μM | References in Mogilner and Edelstein-Keshet (34) |
| η | Geometric conversion coefficient | ∼20 μM−1μm−1 | This article |
| kon | G-actin assembly rate | ≈10 μM−1s−1 | References in Mogilner and Edelstein-Keshet (34) |
| θc | Critical angle between filaments and direction of protrusion | 60–75–80° | Guessed using data from Maly and Borisy and others (4,12) |
| N0 | No. of filaments to support filopodium | ≈13 | This article |
| Vl | Protrusion rate | 0.05 μm/s | (12) |
| b | Rate of bundling | ∼0.01 μm−1s−1 | This article |
| m | Rate of Λ-precursors maturation | ∼0.01/s | This article |
| Vd | Rate of the lateral drift | ∼0.01 μm/s | This article |
| lc | Distance between fascin cross-links | ∼20–200 nm | Guessed using data from Svitkina et al. (12) |