Granés Francesc, Berndt Christine, Roy Christian, Mangeat Paul, Reina Manuel, Vilaró Senén
Department of Cellular Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain.
FEBS Lett. 2003 Jul 17;547(1-3):212-6. doi: 10.1016/s0014-5793(03)00712-9.
ERM (Ezrin/Radixin/Moesin) proteins are crosslinkers between plasma membrane proteins and the actin cytoskeleton, thereby involved in the formation of cell adhesion sites. Earlier work showed that Ezrin links syndecan-2 to the actin cytoskeleton. Here we provide evidence that the Ezrin N-terminal domain binds to the syndecan-2 cytoplasmic domain with an estimated K(D) of 0.71 microM and without the requirement of other proteins. We also studied the regions in the syndecan-2 cytoplasmic domain implicated in the binding to Ezrin. By truncating the syndecan-2 cytoplasmic domain and by oligopeptide competition assays we show that the Ezrin-binding sequence is not located in the positively charged juxtamembrane region (RMRKK), but in the neighboring sequence DEGSYD. We therefore conclude that the consensus sequence for Ezrin binding is unique among membrane proteins, suggesting a distinct regulation.
ERM（埃兹蛋白/根蛋白/膜突蛋白）家族蛋白是质膜蛋白与肌动蛋白细胞骨架之间的交联蛋白，因此参与细胞黏附位点的形成。早期研究表明，埃兹蛋白将多配体蛋白聚糖-2与肌动蛋白细胞骨架相连。在此，我们提供证据表明，埃兹蛋白的N端结构域与多配体蛋白聚糖-2的胞质结构域结合，估计解离常数（K(D)）为0.71微摩尔，且无需其他蛋白参与。我们还研究了多配体蛋白聚糖-2胞质结构域中与埃兹蛋白结合相关的区域。通过截短多配体蛋白聚糖-2的胞质结构域以及进行寡肽竞争试验，我们发现埃兹蛋白结合序列并不位于带正电荷的近膜区域（RMRKK），而是在相邻序列DEGSYD中。因此，我们得出结论，埃兹蛋白结合的共有序列在膜蛋白中是独特的，这表明存在独特的调控机制。
