FIGURE 6.

Proline-rich region does not affect the sequestering and depolymerizing activities of the WH2 domains. A, steady-state anisotropy of Alexa488NHS-Mg²⁺-ATP-G-actin (1 μm) as a function of SALS-Pro-WH2 concentration. Dashed line shows the fit to the data, according to Equation 3. Dissociation equilibrium constant of 0.4 ± 0.2 μm was obtained. Error bars, standard deviation. B, polymerization kinetics of actin (2.5 μm, containing 5% pyrenyl-actin) in the absence and presence of different amounts of SALS-Pro-WH2, as indicated. C, kinetics of actin disassembly (0.02 μm, containing 50% of pyrenyl-actin) in the absence and presence of SALS-WH2 or SALS-Pro-WH2 (12 μm), as indicated. D, polymerization kinetics of actin (2.5 μm, containing 5% pyrenyl-actin) in the absence and presence of profilin (7.3 μm) and/or SALS-Pro-WH2 (6.1 μm), as indicated. a.u., arbitrary units.