Description:
<jats:p>Cross‐linking of actin filaments by filamin by means of frequency‐dependent rheology yields an increase in the filament's elasticity and stiffness. Higher cross‐linker (filamin) ratios are required for mean actin‐filament lengths of 5–6 μm than for random‐length distribution of actin filaments. The loss modulus (i.e. the viscous portion) in the region of the internal‐chain dynamics [<jats:italic>G</jats:italic>′′(ω) ≈ω<jats:sup>α</jats:sup>] is influenced by the cross‐linking of filaments, and with an increasing molar ratio of filamin/actin a reduction of α is observed. Rheological measurements reveal that actin networks are already formed at the polymerizing stage at a molar ratio of filamin/actin of less than 1:100, and electron micrographs show phase separation of actin/filament networks of low density and of actin/filament bundles.</jats:p>