Phalloidin is a toxin from a toadstool (mushroom). You are studying actin dynamics and the effect of phalloidin. You add G-actin
and ATP to a test tube and allow the reaction to come to equilibrium. This produces the light scattering plot below. When you add phalloidin, what will happen to the line?
When we add phalloidin to a solution containing G-actin, the phalloidin binds to actin filaments more tightly as compared to actin monomers which leads to a decrease in the constant rate of dissociation of actin subunits from the ends of the filament. This dissociation stabilizes the actin filaments through the prevention of filament depolymerization. So we can conclude that addition of phalloidin to actin leads to stabilizing of actin filaments.
