FIGURE 6.

Activation of Arp2/3 complex by monomeric and dimeric activators. Pyrene-actin assays were used to monitor the rate of F-actin polymerization with 2 μm actin and 20 nm Arp2/3 complex. Monomeric ActA and VCA are less efficient at catalyzing filament formation than their respective dimeric forms. The right-most graph in both rows displays the slope of the linear phase of the two left graphs with respect to activator concentration. Dimeric ActA and VCA activate the Arp2/3 complex by 2.5- and 20-fold over their respective monomeric forms.