Focal adhesion kinase (FAK) integrates signaling from integrins, growth factor receptors and mechanical stress to control cell adhesion, motility, survival and proliferation. Here, we developed a single-component, photo-activatable FAK, termed optoFAK, by using blue light-induced oligomerization of cryptochrome 2 (CRY2) to activate FAK-CRY2 fusion proteins. OptoFAK functions uncoupled from physiological stimuli and activates downstream signaling rapidly and reversibly upon blue light exposure. OptoFAK stimulates SRC creating a positive feedback loop on FAK activation, facilitating phosphorylation of paxillin and p130Cas in adherent cells. In detached cells or in mechanically stressed adherent cells, optoFAK is autophosphorylated upon exposure to blue light, however, downstream signaling is hampered indicating that the accessibility to these substrates is disturbed. OptoFAK may prove to be a useful tool to study the biological function of FAK in growth factor and integrin signaling, tension-mediated focal adhesion maturation or anoikis and could additionally serve as test system for kinase inhibitors.

粘着斑激酶（FAK）整合了整联蛋白，生长因子受体和机械应激的信号，以控制细胞的粘附，运动性，存活和增殖。在这里，我们通过使用蓝光诱导的隐色染料2（CRY2）寡聚化来激活FAK-CRY2融合蛋白，开发了一种单组分，可光激活的FAK，称为optoFAK。当暴露于蓝光时，OptoFAK的功能与生理刺激无关，并迅速且可逆地激活下游信号。OptoFAK刺激SRC在FAK激活上产生一个正反馈回路，从而促进粘附细胞中的paxillin和p130Cas磷酸化。在分离的细胞或受机械应力的贴壁细胞中，optoFAK在暴露于蓝光时会自动磷酸化，但是，下游信号传输受阻，表明这些基材的可及性受到干扰。OptoFAK可能被证明是研究FAK在生长因子和整联蛋白信号转导，张力介导的粘着力成熟或阳极中的生物学功能的有用工具，并且还可以用作激酶抑制剂的测试系统。