UMR CNRS 5554, Institut des Sciences de l'Evolution, Université Montpellier 2, Place Eugène Bataillon, 34095 Montpellier, Cedex 05, France.
Cytoskeleton (Hoboken). 2010 May;67(5):286-96. doi: 10.1002/cm.20442.
Recent evidences suggest that plastin/fimbrin is more than a simple actin cross-linking molecule. In this context and based on the fact that other members of the same family interact with transmembrane proteins, such as integrins, we have investigated a possible interaction between L-plastin and integrins. By combining coimmunoprecipitation of endogenous proteins and in vitro techniques based on solid phase and solution assays, we demonstrate that L-plastin is an additional binding partner for the beta-chain of integrin and confirmed that both proteins display some colocalization. We then show that L-plastin binds to the cytoplasmic domain of beta1 integrin and to beta1 and beta2 peptides. Using recombinant L-plastin domains, we demonstrate that the integrin-binding sites are not located in NH(2) terminal part of L-plastin but rather in the two actin-binding domains. Using pull-down, cross-linking experiments, and enzyme-linked immunosorbent assay, we show that the L-plastin/integrin complex is regulated by mu-calpain cleavage and is not directly dissociated by calcium. Indeed, despite the ability of calpain to cleave both proteins, only the cleavage of beta integrin hindered the formation of the L-plastin/integrin complex. We discuss these results in the light of the three-dimensional structure of the actin-binding domains of L-plastin.
最近的证据表明，韧丝蛋白不只是一种简单的肌动蛋白交联分子。在这种情况下，并且基于同一家族的其他成员与跨膜蛋白（如整合素）相互作用的事实，我们研究了 L-韧丝蛋白与整合素之间可能存在的相互作用。通过结合内源性蛋白质的共免疫沉淀和基于固相和溶液测定的体外技术，我们证明 L-韧丝蛋白是整合素β链的另一个结合伴侣，并证实这两种蛋白质显示出一些共定位。然后，我们表明 L-韧丝蛋白与β 1 整合素的胞质结构域以及β 1 和β 2 肽结合。使用重组 L-韧丝蛋白结构域，我们证明整合素结合位点不在 L-韧丝蛋白的 NH2 端部分，而是在两个肌动蛋白结合结构域中。通过下拉、交联实验和酶联免疫吸附试验，我们表明 L-韧丝蛋白/整合素复合物受钙蛋白酶切割调节，并且不受钙直接解离。实际上，尽管钙蛋白酶能够切割这两种蛋白质，但只有β 整合素的切割会阻碍 L-韧丝蛋白/整合素复合物的形成。我们根据 L-韧丝蛋白肌动蛋白结合结构域的三维结构讨论了这些结果。
