VAV exchanges GTP for GDP on RAC1, activating it

Tyrosine-phosphorylated VAVs act as guanine nucleotide exchange factors (GEFs) for RAC1, catalysing the exchange of bound GDP for GTP. RAC1 is a key regulator for actin cytoskeleton and cell migration and is also a critical component of endothelial NADPH oxidase (Wittmann et al. 2003, Tan et al. 2008, Ushio–Fukai 2007, Pricei et al. 2002). Activated RAC1 then stimulates actin polymerization to form lamellipodia through a number of proteins such as WASP-family veroprilin homologous protein (WAV). WAVE proteins stimulate the formation of a branched actin network by binding to the p21 subunit of the ARP2/3 nucleating complex, which is located on the sides of the pre-existing filaments.

酪氨酸磷酸化的VAVs作为RAC1的鸟苷酸交换因子（GEFs），催化结合GDP与GTP的交换。RAC1是细胞骨架和细胞迁移的关键调节因子，亦是内皮NADPH氧化酶（Wittmann等，2003年，Tan等，2008年，Ushio-Fukai，2007年，Pricei等，2002年）的关键组成部分。激活后的RAC1通过一系列蛋白质如WASP家族veroprilin同源蛋白（WAV）刺激肌动蛋白聚合，形成层状伪足。WAVE蛋白通过与ARP2/3核化复合物的p21亚基结合，促进分支肌动蛋白网络的生成，该复合物位于现有丝状伪足的侧面。