Figure 2.

Actin cross-linking proteins (ACPs) regulate contractile behaviors of networks. We changed ACP density (R_ACP) between 0.0025 and 0.16 at R_M = 0.04, <L_f> = 1.6 μm, and k_t,A = 30 s⁻¹. (a) The morphology of networks at 65 s depending on R_ACP. At small R_ACP, networks are quite homogeneous. As R_ACP increases, networks severely aggregate into disconnected clusters. At large R_ACP, very high network connectivity precludes formation of separated clusters, leading to interconnected bundles. (b) The heterogeneity of F-actin distribution (blue circle) and $\langle \cos \varphi \rangle$ representing persistency of motor velocities between 10 and 20 s (red triangle) depending on R_ACP. Consistent with (a), the heterogeneity is the highest at intermediate levels of R_ACP, and velocities of motors exhibit the most persistent motions. (c) The average speed of motors at early times (0–10 s, blue square) and late times (from 50 s till end, red triangle). Motors initially move at the highest speed at intermediate levels of R_ACP at which the largest contraction emerges. Regardless of R_ACP, the average speed is substantially decreased over time. To see this figure in color, go online.