FIGURE 5.

Copolymerization of G-actin with either Bnr1orBni1. Mg-G-actin (5% pyrene-labeled), 1 μm, was mixed with either Bnr1 (panel A) or Bni1 (panel B) for 15 min and was then induced to polymerize by the addition of MgCl₂ and KCl to final concentrations of 2 mm and 50 mm, respectively. The increase in pyrene fluorescence over time was recorded as described under “Experimental Procedures.” These experiments have been repeated three times with essentially identical results, and only one data set is presented. Panel A, Bnr1 concentrations are no formin (○), 3.3 μm (Õ), 10 μm (▵), 50 μm (♢), and 150 μm (□). Panel B, Bnr1 concentrations are no formin (○), 10 μm (▵), 50 μm (♢), and 150 μm (□). Arrow, time of addition of salt.