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. 2013 Apr 16;104(8):1709–1719. doi: 10.1016/j.bpj.2013.01.017

Figure 4.

Figure 4

Network gelation is inhibited at low filament elongation rates. (A) Time course of the spontaneous assembly of 5 μM Mg-ATP-actin monomers (10% pyrene labeled) in the presence of 500 nM Cdc12 and the indicated concentrations of SpPrf. (B) Calculated barbed end concentration from (A) and elongation rate per formin-bound filament as a function of SpPrf concentration. (C) Representative images of fluorescent (Alexa 488) phalloidin labeling of F-actin in networks forming via a spontaneous assembling of 5 μM Mg-ATP-actin, 1.2 μM α-actinin, and 500 nM Cdc12 in the presence of varying concentrations of SpPrf. Polymerization is initiated at 0 s; scale bar = 30 μm. (D) The time to steady-state bundle density (open squares), structure factor S(q,t) (solid circles), and dynamic arrest (solid diamonds) for the samples described above as a function of SpPrf concentration. (E) The mean instantaneous speed as a function of time for bundles formed with 0.5 μM Cdc12 (black square), 3.3 μM Cdc12 (open circles, 5 μM Cdc12 (solid triangles), and 15 μM Cdc12 (solid circles). Only samples with 5 and 15 μM Cdc12 reached the threshold for dynamic arrest (horizontal dashed line). (F) Steady-state linear bundle density for samples with 500 nM Cdc12 as a function of SpPrf concentration.