Figure 4.

Comparison of motor-distribution models to the observed filament shape (A) A uniform force distribution (left panel, red curve) produces a spiral shape (right panel, red curve). Tip-concentrated force distributions (left panel, blue and green curves) produce nearly circular arcs (right panel, blue and green curves). (B and C) Curvature and tangent angle data (black dots) from Fig. 2B compared to the models. (Green lines) Curvature control, with κ = 120 pN⋅μm², a₀ = 60 nm, ρ = 200 μm⁻¹, f₊ = 5 pN, and C_c = 0.25 μm⁻¹. (Blue lines) Normal-force control with f_c = 200 pN⋅μm⁻¹. (Red lines) Absence of motor regulation, with a uniform force density of f_m = 500 pN⋅μm⁻¹. The force density was chosen to match the data for the maximum angle at the filament tip. To see this figure in color, go online.