Figure 4: Schematic representation of FH2 dimer translocation at the barbed end of an actin filament.
From: Formin mDia1 senses and generates mechanical forces on actin filaments
The filament barbed end is in a non-polymerizing state when the FH2 dimer is in the ‘closed’ conformation, while it can bind an actin monomer (not shown) when the FH2 dimer is in the ‘open’ conformation15. When analysing filament depolymerization, we consider that the FH2 dimer in the ‘open’ conformation prevents the departure of the terminal actin subunit from the barbed end. Applying a pulling force tilts the energy landscape of the FH2 dimer at the barbed end, favouring the ‘open’ conformation. In the frame of reference of the microchamber, the FH2 dimer is in a fixed location and the filament is displaced as it elongates or depolymerizes.
