Activation of Talin

Talin is one of the major cytoskeletal proteins involved in integrin activation and linking the resulting focal adhesion (FA) with cytoskeleton. Talin comprises an N-ter head region and a flexible rod domain. The head region has the FERM domain (subdivided into F1, F2 and F3 subdomains), which has the binding sites for beta integrin cytoplasmic regions and actin binding sites close to the C-terminal rod domain. <br>Talin exists in closed inactive conformation, where the head region interacts with the rod domain masking the integrin binding sites. At the plasma membrane the RIAM bound to active Rap1 recruits talin to form the integrin activation complex. This interaction exposes the integrin-binding site in talin F3 domain leading to integrin activation. <br>

Talin作为一种关键的细胞骨架蛋白，在整合素激活过程中发挥着至关重要的作用，并负责将由此产生的焦点粘附（FA）与细胞骨架相连接。Talin蛋白由一个N端头部区域和一个灵活的棒状区域组成。头部区域包含FERM结构域（进一步分为F1、F2和F3亚域），该结构域具有与β整合素细胞质区域以及靠近C端棒状区域的肌动蛋白结合位点。Talin存在于闭合的非活性构象中，此时头部区域与棒状区域相互作用，掩盖了整合素结合位点。在质膜上，与活跃的Rap1结合的RIAM招募Talin形成整合素激活复合物。这种相互作用暴露了Talin F3域中的整合素结合位点，从而引发整合素的激活。