VISCOELASTICITY OF ACTIN-GELSOLIN NETWORKS IN THE PRESENCE OF FILAMIN

Cross-linking of actin filaments by filamin by means of frequency-depe ndent rheology yields an increase in the filament's elasticity and sti ffness. Higher cross-linker (filamin) ratios are required for mean act in-filament lengths of 5-6 mu m than for random-length distribution of actin filaments. The loss modulus (i.e. the viscous portion) in the r egion of the internal-chain dynamics [G''(omega) approximate to omega( alpha)] is influenced by the cross-linking of filaments, and with an i ncreasing molar ratio of filamin/actin a reduction of a is observed. R heological measurements reveal that actin networks are already formed at the polymerizing stage at a molar ratio of filamin/actin of less th an 1:100, and electron micrographs show phase separation of actin/fila ment networks of low density and of actin/filament bundles.