2.2 Assembly Mechanism of actin polymerization: 3 phases of G- actin polymerization Q Critical concentration(Cc). In steady state, G-actin monomers only exchange with subunits at the filament ends but there is no net change in the total mass of filaments During the elongation state, one end of the filament the (+)end elongates five to ten times faster than does the opposite ()end. This is because Cc value is much lower for G-actin addition at the(+)end than for addition at the(-)end2.2 Assembly ◆ Mechanism of actin polymerization: 3 phases of G￾actin polymerization. ◆ Critical concentration (Cc). In steady state, G-actin monomers only exchange with subunits at the filament ends but there is no net change in the total mass of filaments. ◆ During the elongation state, one end of the filament, the (+) end, elongates five to ten times faster than does the opposite (-) end. This is because Cc value is much lower for G-actin addition at the (+) end than for addition at the (-) end