Fig. 8

Schematic of proposed CARMIL3 function during synapse development. (1) In the absence of CARMIL3 and capping protein, monomeric (G-actin) is preferentially added to the barbed (+) ends of filamentous actin (F-actin). (2) CARMIL3 bound to capping protein is recruited to the membrane of developing protrusions through its interaction with Wrp. (3) Capping protein binds to the barbed ends of actin filaments, preventing the addition of G-actin. (4) G-actin is now primed for nucleation by the Arp2/3 complex, which shifts the actin dynamics of the developing synapse from largely linear actin to a dense, branched actin network required for synaptic maturation