Effect of Cibachron Blue F3GA on the polymerization of actin.

The effect of the dye Cibachron Blue F3GA on the G-F transformation of rabbit muscle actin has been studied with viscosimetry. The presence of the dye which is known to bind to nucleotide binding sites, decreased both the initial rate of polymerization of actin as well as the final viscosity of actin. Both these effects can be ascribed to an increase in the critical concentration of actin. The inhibitory effect of Cibachron Blue F3GA was counteracted by ATP, suggesting a competition between Cibachron Blue F3GA and ATP for the binding site/sites on actin.