Figure 4.

(a) Average local concentration [A] of monomeric G-actins available for polymerization near the membrane is shown as a function of G-actin concentration in the rear of the reaction front (i.e., bulk G-actin concentration). Local actins are these actins within the particular compartment in which a polymerization event occurs. (b) The average load 〈w〉 experienced by polymerizing filaments as a function of rear G-actin concentration. The load w diminishes the polymerization rate through the term $e^{-w/K_{\text{B}}T}$.