Figure 1.

Actin polymerization and steady state treadmilling. The G-actin monomers attach to the continually growing barbed (+) end of the filament in a more stable ATP-state to form F-actin strands, which in cells function to support structural integrity during cell division and migration. Upon ATP-hydrolysis-driven F-actin depolymerization, ADP monomers begin to dissociate from the pointed (-) end of the filament at a faster rate than the ATP monomers are bound. This process of steady-state actin polymerization and depolymerization is known as treadmilling. The dynamic regulation of actin elongation is accelerated/decelerated via an action of profilin and ADF/cofilin.