Evidence that cytochalasins reduce the size of polymerization nuclei during actin polymerization.

In a double-logarithmic plot of the rate of actin polymerization against monomer concentration, the slope has a lower value in the presence of the fungal metabolites cytochalasin B and D than in their absence. This suggests that actin oligomers which serve as polymerization nuclei are smaller in the presence of cytochalasins than in their absence.