Figure 3: Ca2+-dependence of in vitro motility speed for regulated thin filaments reconstituted with HcTn and either, (a) α-GS-Tm WT (•), (b) α-GS-Tm V95A (), (c) α-GS-Tm D175N (), or (d) α-GS-Tm E180G (■). In (b–d), data and regressions for each Tm were normalized to from regression (4) for the same Tm. Each point represents the mean for one flow cell; error bars in (b–d) are comparable to those in (a). Solid lines are nonlinear least squares regression fits of the mutant Tm data to (4), and parameter estimates are given in Table 1. For comparison, the regression line for α-GS-Tm WT (a) was normalized as described above and plotted in panels (b–d) as a dotted line for reference.