Turunen O, Wahlström T, Vaheri A
Haartman Institute, Department of Virology, Helsinki University, Finland.
J Cell Biol. 1994 Sep;126(6):1445-53. doi: 10.1083/jcb.126.6.1445.
Ezrin, previously also known as cytovillin, p81, and 80K, is a cytoplasmic protein enriched in microvilli and other cell surface structures. Ezrin is postulated to have a membrane-cytoskeleton linker role. Recent findings have also revealed that the NH2-terminal domain of ezrin is associated with the plasma membrane and the COOH-terminal domain with the cytoskeleton (Algrain, M., O. Turunen, A. Vaheri, D. Louvard, and M. Arpin. 1993. J. Cell Biol. 120: 129-139). Using bacterially expressed fragments of ezrin we now demonstrate that ezrin has an actin-binding capability. We used glutathione-S-transferase fusion proteins of truncated ezrin in affinity chromatography to bind actin from the cell extract or purified rabbit muscle actin. We detected a binding site for filamentous actin that was localized to the COOH-terminal 34 amino acids of ezrin. No binding of monomeric actin was detected in the assay. The region corresponding to the COOH-terminal actin-binding site in ezrin is highly conserved in moesin, actin-capping protein radixin and EM10 protein of E. multilocularis, but not in merlin/schwannomin. Consequently, this site is a potential actin-binding site also in the other members of the protein family. Furthermore, the actin-binding site in ezrin shows sequence homology to the actin-binding site in the COOH terminus of the beta subunit of the actin-capping protein CapZ and one of the potential actin-binding sites in myosin heavy chain. The actin-binding capability of ezrin supports its proposed role as a membrane-cytoskeleton linker.
埃兹蛋白，以前也被称为细胞绒毛蛋白、p81和80K，是一种富含于微绒毛和其他细胞表面结构中的细胞质蛋白。据推测，埃兹蛋白具有膜 - 细胞骨架连接蛋白的作用。最近的研究结果还表明，埃兹蛋白的氨基末端结构域与质膜相关，而羧基末端结构域与细胞骨架相关（阿尔格兰，M.，O. 图鲁嫩，A. 瓦赫里，D. 卢瓦尔，和M. 阿尔潘。1993年。《细胞生物学杂志》120: 129 - 139）。现在我们利用细菌表达的埃兹蛋白片段证明了埃兹蛋白具有肌动蛋白结合能力。我们使用截短的埃兹蛋白的谷胱甘肽 - S - 转移酶融合蛋白在亲和色谱中从细胞提取物或纯化的兔肌肉肌动蛋白中结合肌动蛋白。我们检测到丝状肌动蛋白的一个结合位点，该位点定位于埃兹蛋白的羧基末端34个氨基酸。在该检测中未检测到单体肌动蛋白的结合。埃兹蛋白中与羧基末端肌动蛋白结合位点相对应的区域在埃兹蛋白、肌动蛋白封端蛋白根蛋白和多房棘球绦虫EM10蛋白中高度保守，但在默林/施万诺明中不保守。因此，该位点也是该蛋白家族其他成员中潜在的肌动蛋白结合位点。此外，埃兹蛋白中的肌动蛋白结合位点与肌动蛋白封端蛋白CapZ的β亚基羧基末端的肌动蛋白结合位点以及肌球蛋白重链中一个潜在的肌动蛋白结合位点具有序列同源性。埃兹蛋白的肌动蛋白结合能力支持了其作为膜 - 细胞骨架连接蛋白的推测作用。
