Skip to main content
. 2012 Mar 7;102(5):1049–1058. doi: 10.1016/j.bpj.2012.01.030

Figure 1.

Figure 1

Actin network growth from a surface. (A) Sketch of an actin network (red mesh) growing from a surface (gray) where actin nucleators (blue) are located. The surface is locally subject to an external normal stress σnn and the network grows at velocity vp. The actin filaments interacting with the surface can be either associated to nucleators or dissociated from them. Dissociated filaments, which polymerize toward the surface and generate an average pushing force fd, associate to nucleators at a rate ka. Filaments associated to nucleators resist the growth with an average force fa per filament and dissociate from nucleators at a rate kd. (B) Nature of the resistive force: After their initial attachment to a nucleator at the surface, attached filaments are continuously loaded by network growth during their lifetime. The initial attachment of a detached filament to a surface nucleator at t = 0 does not impose any instantaneous stretch on either the actin network or the new filament-nucleator link. Once attached to the surface, the new attached filament resists an increasing load over time as a result of network elongation. After a time t, the network has advanced a distance vpt, and the combination of this network elongation with the attachment of the filament at the surface generates deformations δ(t) and δ(t) of the actin network and filament-nucleator link, respectively. (In color online.)