Figure 1.
Gelation kinetics of actin filament networks in the presence of equimolar concentrations of F-actin crosslinking proteins α-actinin, and filamin.
Time-dependent elastic modulus is measured using a strain-controlled rheometer. The imposed deformation amplitude to measure the elastic modulus was 1% and the shear frequency was 1 rad/s. The concentration of actin was 24 μM.
Figure 2.
Elastic modulus of F-actin networks in the presence of α-actinin, filamin or both.
Steady state elastic modulus of F-actin networks in the presence of α-actinin only (black columns), both filamin and α-actinin (50:50 molar ratio; grey columns), or filamin only (blue columns). was measured using a strain-controlled rheometer. The total concentration of F-actin crosslinking proteins is indicated. The imposed deformation amplitude to measure the elastic modulus was 1% and the shear frequency was 1 rad/s. The concentration of actin was 24 μM.
Figure 3.
Viscoelastic properties of F-actin networks in the presence of α-actinin, filamin or both.
A. Frequency-dependent elastic modulus of F-actin networks in the presence of either 0.12 μM α-actinin, 0.12 μM filamin, or 0.06 μM α-actinin+0.06 μM filamin. The amplitude of the deformation was 1%. Elastic moduli are normalized by their value at 1 rad/s. B. Slope a of the elastic modulus obtained from a power-law fit of G'(ω)∼ωa shown in panel A. C. Phase angle of F-actin networks, which compares the viscous modulus G” to the elastic modulus, G' as δ = tan−1(G”/G'). The phase angle of water and F-actin without crosslinking proteins is 90° and 30°, respectively.
Figure 4.
Non-linear rheology of F-actin networks in the presence of α-actinin, filamin or both.
A and B. Time-dependent shear modulus G(t, γ0) of an F-actin network in the presence of (A) both α-actinin and filamin or (B) filamin alone for low shear deformation amplitude γ0. The modulus increases for increasing deformation amplitudes, indicating shear-induced network hardening (or stiffening). Inset, Time-dependent shear modulus of the same network for high deformation amplitudes. The modulus decreases for increasing deformation amplitude, indicating shear-induced network softening. C. Shear modulus of F-actin networks in the presence of α-actinin, filamin, or both as a function of deformation amplitude. The modulus is estimated at a time of 1 second.