Limk1 phosphorylates Cfl1, inactivating it

The EPHB2-FAK pathway partially promotes dendritic spine stability through LIMK-mediated cofilin (CFL1) phosphorylation (Shi et al. 2009). CFL1 is a member of the ADF (actin-depolymerizing factor) protein family that is involved in regulating actin dynamics in the growth cone. It binds to actin in a one-to-one molar ratio, and stimulates both the severing of actin filaments and depolymerization of actin subunits from the actin filament end. Activated LIMK phosphorylates CFL1 on the conserved serine 3 residue located near the actin-binding site. After phosphorylation, CFL1 is inactive, loses its affinity for actin and dissociates from G-actin monomers. Once freed, ADP-actin monomers can exchange ADP with cytoplasmic ATP, ready for reincorporation at the barbed end of a growing filament (Gungabissoon & Bamburg 2003).

EPHB2-FAK通路部分促进树突棘的稳定性，这一作用通过LIMK介导的Cofilin（CFL1）磷酸化实现（Shi等，2009年）。CFL1是ADF（肌动蛋白去聚合因子）蛋白家族的成员，该家族在调节生长锥中的肌动蛋白动态过程中发挥重要作用。CFL1以一比一的摩尔比例与肌动蛋白结合，并刺激肌动蛋白丝的切断以及从肌动蛋白丝末端解聚肌动蛋白亚基。激活的LIMK在位于肌动蛋白结合位点附近的保守丝氨酸3残基上磷酸化CFL1。磷酸化后，CFL1失活，失去对肌动蛋白的结合亲和力，并从G-肌动蛋白单体中解离。一旦释放，ADP-肌动蛋白单体可以与细胞质中的ATP交换ADP，准备在正在生长的丝的尖端重新结合（Gungabissoon & Bamburg，2003年）。