FIGURE 3.

The effect of the distance between a single FH1 polyproline track pPD and the FH2 domain on Bni1p-mediated polymerization. Conditions: 1.5 μm actin (33% Oregon Green) in microscopy buffer with a range of profilin concentrations. Data were collected by TIRFM. Dependence of the FH1-stimulated barbed-end elongation rate of Bni1(pPD₁₈FH2)p- (black), Bni1(pPD₂₈FH2)p- (green), Bni1(pPD₃₇FH2)p- (blue), and Bni1(pPD₆₅FH2)p- (red) associated filaments on the concentration of profilin. The rate of FH2-mediated polymerization without profilin was subtracted from the polymerization rate measured at each profilin concentration to give the contribution of the pPD track to polymerization. The error bars are S.E.