Sato N, Funayama N, Nagafuchi A, Yonemura S, Tsukita S, Tsukita S
Department of Information Physiology, National Institute for Physiological Sciences, Aichi, Japan.
J Cell Sci. 1992 Sep;103 ( Pt 1):131-43. doi: 10.1242/jcs.103.1.131.
Radixin is a barbed end-capping actin-modulating protein which was previously reported to be concentrated at cell-to-cell adherens junctions (AJ) and cleavage furrows. Recently, cDNA encoding mouse radixin was isolated, showing that radixin is highly homologous to but distinct from ezrin. From mouse teratocarcinoma cells we isolated and analyzed cDNA encoding another radixin-related protein. Sequence analysis has demonstrated that this protein is a mouse homologue of human moesin (98.3% identity) and that it shares 71.7% and 80.1% identity with ezrin and radixin, respectively. Translation experiments in vitro combined with immunoblot analyses led us to conclude that there is a gene family consisting of ezrin, radixin and moesin. These members are coexpressed in various types of cells. Then, by immunofluorescence microscopy, we closely analyzed their distribution using polyclonal and monoclonal antibodies, which could recognize all three members. In addition to cell-to-cell AJ and cleavage furrows, it was shown that they were concentrated at microvilli and ruffling membranes in various types of cells. Furthermore, the cell-to-substrate AJ (focal contacts) were clearly stained by anti-radixin pAb only after the apical/lateral membranes and cytoplasm were removed by the zinc method. We conclude that at least one of the members of the ezrin-radixin-moesin family is concentrated at specific regions where actin filaments are densely associated with plasma membranes.
根蛋白是一种带刺的末端封闭肌动蛋白调节蛋白，先前报道它集中在细胞间黏附连接（AJ）和分裂沟处。最近，编码小鼠根蛋白的cDNA被分离出来，表明根蛋白与埃兹蛋白高度同源但又有所不同。我们从小鼠畸胎瘤细胞中分离并分析了编码另一种根蛋白相关蛋白的cDNA。序列分析表明，这种蛋白是人类埃莫辛的小鼠同源物（同一性为98.3%），并且它与埃兹蛋白和根蛋白的同一性分别为71.7%和80.1%。体外翻译实验结合免疫印迹分析使我们得出结论，存在一个由埃兹蛋白、根蛋白和埃莫辛组成的基因家族。这些成员在各种类型的细胞中共同表达。然后，通过免疫荧光显微镜，我们使用能够识别所有三个成员的多克隆和单克隆抗体仔细分析了它们的分布。除了细胞间AJ和分裂沟外，还表明它们集中在各种类型细胞的微绒毛和褶皱膜处。此外，只有在用锌法去除顶端/侧面膜和细胞质后，抗根蛋白pAb才能清晰地染色细胞与底物的AJ（黏着斑）。我们得出结论，埃兹蛋白-根蛋白-埃莫辛家族的至少一个成员集中在肌动蛋白丝与质膜紧密相关的特定区域。
