Fig. 9. Twf1 accelerates actin assembly seeded by pre-formed filaments. 3 µM monomeric actin (2% pyrene labeled) and 10 µM S. cerevisiae profilin were pre-mixed and added at time zero to 0.3 µM pre-formed actin filaments (F-actin) and 500 nM Cof1, 500 nM Twf1, or control buffer (3 µM actin) at pH 5.0. A.U., arbitrary units.