SRGAP2 stimulates RAC1 GTP-ase activity and ends FMNL1-mediated elongation of actin filaments

SRGAP2 is a GTPase activating protein that stimulates the GTPase activity of RAC1 bound to FMNL1. GTP hydrolysis produces inactive GDP-bound RAC1 which is unable to bind and activate FMNL1. SRGAP2 thereby limits the duration of FMNL1-mediated elongation of actin filaments downstream of RAC1:GTP (Mason et al. 2011).

SRGAP2（Rho GTPase 激活蛋白）通过激活与FMNL1结合的RAC1的GTPase活性发挥作用。GTP的水解生成非活性GDP结合的RAC1，该RAC1无法结合并激活FMNL1。因此，SRGAP2限制了RAC1:GTP下游由FMNL1介导的肌动蛋白丝延伸的持续时间（Mason等，2011年）。