Model of CPI motif regulation of CP during CME. Top: In WT cells, CP is recruited to CME sites through interaction with the CPI motifs of Aim21 and Bsp1, and to a lesser degree through freely binding F-actin barbed ends. Following CP binding to barbed ends, Aim21 and Bsp1 dissociate from CP and allow Twf1 to bind CP through its CPI motif. Twf1 functions to remove CP from barbed ends through its ADF-H domains. The removal of CP and the exposure of aged barbed ends allow for efficient turnover of the branched actin network. Middle: In cells with non-functional Aim21 and Bsp1 motifs, there is a severe CP recruitment defect, leading to reduced recruitment of Twf1. The lack of CP results in an overgrown actin network and elevated levels of Aim21 and Bsp1. The overgrown actin network is turned over at a slower rate due to reduced levels of Twf1. Bottom: In cells with a non-functional Twf1 CPI motif, CP is recruited through Aim21 and Bsp1, but Twf1 is not properly recruited following CP binding to barbed ends. CP is not removed from aged barbed ends by Twf1, and the rate of turnover of the actin network is reduced.