Fig. 2

Actin assembly induces a local monomer depletion that controls the growth rate of branched actin networks. a LMs were constrained as in c and grown from 3 × 15 µm² NPF-coated bars either spaced by 25 or 6 µm. b The growth rate was measured at 30 min. Error bars show mean s.d. for n LMs per condition, n = 18 from four experiments (25 µm), n = 16 from six experiments (6 µm). c–f Actin assembly was followed for LMs growing from NPF-coated nucleation bars of 3 µm width and increasing length, as mentioned. The growth was followed for 2D-like configuration in small volume with 4.5 µm space between glass and coverslip c, d, e, or for 3D-like configuration in a larger reconstituted volume with 70 µm space between glass and coverslip f, g, h. e, h 2D- and 3D-growth rates measured in each case (open black symbols). Mathematical modeling (red symbols in e, h) of the experimental growth rates measured in d, g. Error bars show mean s.d. for n LMs, n = 19 from four experiments (15 µm), n = 23 from seven experiments (30 µm), and n = 16 from four different experiments (90 µm) in e and n = 14 from six experiments (15 µm), n = 12 from six experiments (30 µm), and n = 16 from six experiments (90 µm) in h. a, d, g LM growth was reconstituted with the standard purified medium containing actin-profilin complex, Arp2/3 complex and capping protein, as described in the Methods section. All specified lengths are in µm (see also related Supplementary Figs 3, 4, 5 and 6). Scale bars in are 15 µm