From the Department of Molecular Biology and Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853.
J Biol Chem. 2013 Dec 6;288(49):35437-51. doi: 10.1074/jbc.M113.505669. Epub 2013 Oct 22.
Ezrin, a member of the ezrin-radixin-moesin family (ERM), is an essential regulator of the structure of microvilli on the apical aspect of epithelial cells. Ezrin provides a linkage between membrane-associated proteins and F-actin, oscillating between active/open and inactive/closed states, and is regulated in part by phosphorylation of a C-terminal threonine. In the open state, ezrin can bind a number of ligands, but in the closed state the ligand-binding sites are inaccessible. In vitro analysis has proposed that there may be a third hyperactivated form of ezrin. To gain a better understanding of ezrin, we conducted an unbiased proteomic analysis of ezrin-binding proteins in an epithelial cell line, Jeg-3. We refined our list of interactors by comparing the interactomes using quantitative mass spectrometry between wild-type ezrin, closed ezrin, open ezrin, and hyperactivated ezrin. The analysis reveals several novel interactors confirmed by their localization to microvilli, as well as a significant class of proteins that bind closed ezrin. Taken together, the data indicate that ezrin can exist in three different conformational states, and different ligands "perceive" ezrin conformational states differently.
埃兹蛋白（Ezrin）是埃兹蛋白-根蛋白-膜突蛋白（ERM）家族的一员，是上皮细胞顶侧微绒毛结构的重要调节剂。埃兹蛋白提供了膜相关蛋白与 F-肌动蛋白之间的连接，在活性/开放和非活性/关闭状态之间振荡，并部分受 C 末端苏氨酸磷酸化的调节。在开放状态下，埃兹蛋白可以结合许多配体，但在关闭状态下，配体结合位点无法进入。体外分析表明，埃兹蛋白可能存在第三种超激活形式。为了更好地了解埃兹蛋白，我们在 Jeg-3 上皮细胞系中对埃兹蛋白结合蛋白进行了无偏蛋白质组学分析。我们通过比较野生型埃兹蛋白、封闭型埃兹蛋白、开放型埃兹蛋白和超激活型埃兹蛋白之间的相互作用组，对相互作用体列表进行了细化。该分析揭示了几种通过定位于微绒毛得到证实的新相互作用体，以及一类与封闭型埃兹蛋白结合的重要蛋白质。总的来说，这些数据表明埃兹蛋白可以存在于三种不同的构象状态中，并且不同的配体对埃兹蛋白构象状态的感知方式不同。
