FIGURE 5.

SALS-WH2 binds and enhances the disassembly of actin filaments, which is influenced by actin-binding drugs and tropomyosin. A, left panel, kinetics of actin disassembly (0.02 μm, containing 50% pyrenyl-actin) in the absence and presence of different amount of SALS-WH2, as indicated. Right panel, as controls, actin disassembly kinetics in the presence of latrunculin A (20 μm) or gelsolin (0.1 and 0.5 μm) are shown. B, relative pyrenyl fluorescence of F-actin (1 μm) in the presence of increasing amounts of SALS-WH2, in the absence and presence of phalloidin (1 μm) or jasplakinolide (1 μm), as indicated. The relative pyrenyl fluorescence corresponding to G-actin is shown as a gray dot. C, ratio of SALS-WH2 and actin in the pellet as the function of SALS-WH2 concentration determined from high speed sedimentation experiments using actin filaments (2.5 μm) stabilized by equimolar amount of phalloidin. D, kinetics of actin disassembly (0.02 μm, containing 50% pyrenyl-actin) in the presence of tropomyosin (4.5 μm) and in the absence and presence of different amount of SALS-WH2, as indicated. For easier comparison, gray line shows the pyrenyl trace obtained in the absence of tropomyosin and in the presence of SALS-WH2 (12.5 μm) (same data is shown on A). E, relative pyrenyl fluorescence of F-actin (1 μm) and tropomyosin (4.5 μm) decorated F-actin in the presence of increasing amounts of SALS-WH2, as indicated. The relative pyrenyl fluorescence corresponding to G-actin is shown as a gray dot.