FIGURE 7.

Model of srGAP2 bi-modal regulation of FMNL1-actin signaling during phagocytosis. A, FMNL1 is basally inhibited and cytosolic. Upon activation by Rac (B) FMNL1 translocates to the membrane, and the active form of FMNL1 can bind and sever actin filaments. This potentially regulates Fc-γ receptor-mediated phagocytosis in macrophages. C, in this active state srGAP2 can bind FMNL1 at the membrane to inactivate the Rac signal (1) and inhibit the severing activity of FMNL1 (2). This would return FMNL1 to its quiescent, inactive state. This recycling mechanism could be responsible for rapid turnover of actin filaments and Rac signaling during phagocytosis. DD stands for dimerization domain.