Fig. 7. A schematic model of co-operation between CAP1 and cofilin in promotion of actin dynamics. The working steps of CAP1 are indicated by open arrowheads. (1) CAP1 facilitates the addition of Mg-ATP-actin monomer onto the barbed end of actin filament. Cofilin-induced severing also contributes to this step by increasing the number of barbed ends. (2) CAP1 accelerates subunit release at the pointed end and enhances the more potent, analogous effect of cofilin. (3) CAP1 relieves the inhibitory effect of cofilin on nucleotide exchange of ADP-actin. (4) CAP1 accelerates nucleotide exchange on G-actin.