Figure 4. Illustration of a one-dimensional model of motors inside a linear protrusion, moving along unipolar filaments.
Free motors (light blue) diffuse (with diffusion coefficient D), bound motors (red) drift towards the protrusion base at the treadmilling velocity vb, and processively walking motors (blue) with velocity vw − vb towards the tip. Reversible transitions are assumed between all states (red arrows).