Ezrin/radixin/moesin (ERM) proteins bind to a positively charged amino acid cluster in the juxta-membrane cytoplasmic domain of CD44, CD43, and ICAM-2.
Ezrin/radixin/moesin (ERM) proteins bind to a positively charged amino acid cluster in the juxta-membrane cytoplasmic domain of CD44, CD43, and ICAM-2.
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DOI：
10.1083/jcb.140.4.885
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发表时间：
1998-02-23
期刊：
影响因子：
--
通讯作者：
Tsukita S
中科院分区：
文献类型：
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作者：
Yonemura S;Hirao M;Doi Y;Takahashi N;Kondo T;Tsukita S;Tsukita S
抽象的。 CD44 已被确定为 ezrin/radixin/moesin (ERM) 蛋白、质膜/肌动蛋白丝交联剂的膜结合伴侣。然而，ERM 蛋白不一定与组织中的 CD44 共定位，但在某些类型的细胞中与 CD43 和 ICAM-2 共定位。我们发现，具有 CD43 和 ICAM-2 胞质结构域以及 CD44 的谷胱甘肽-S-转移酶融合蛋白在体外与 moesin 结合。负责 CD43 和 CD44 与 moesin 体外结合的区域被缩小到细胞质结构域中的近膜 20-30 个氨基酸序列。这些序列和 ICAM-2 的胞质结构域（28 个氨基酸）均以带正电荷的氨基酸簇为特征。当携带这些带正电荷的 CD44、CD43 或 ICAM-2 氨基酸簇的 E-钙粘蛋白嵌合分子在小鼠 L 成纤维细胞中表达时，它们与 ERM 蛋白共同集中在微绒毛处，而缺乏这些簇的 E-钙粘蛋白嵌合分子则广泛分布在细胞表面。通过免疫沉淀和定点诱变证实了 ERM 蛋白与 CD44、CD43 和 ICAM-2 的近膜带正电氨基酸簇的特异性结合。根据这些发现，我们得出结论，ERM 蛋白与在其近膜胞质结构域中带有带正电荷的氨基酸簇的整合膜蛋白结合。
Abstract. CD44 has been identified as a membrane-binding partner for ezrin/radixin/moesin (ERM) proteins, plasma membrane/actin filament cross-linkers. ERM proteins, however, are not necessarily colocalized with CD44 in tissues, but with CD43 and ICAM-2 in some types of cells. We found that glutathione-S-transferase fusion proteins with the cytoplasmic domain of CD43 and ICAM-2, as well as CD44, bound to moesin in vitro. The regions responsible for the in vitro binding of CD43 and CD44 to moesin were narrowed down to their juxta-membrane 20–30–amino acid sequences in the cytoplasmic domain. These sequences and the cytoplasmic domain of ICAM-2 (28 amino acids) were all characterized by the positively charged amino acid clusters. When E-cadherin chimeric molecules bearing these positively charged amino acid clusters of CD44, CD43, or ICAM-2 were expressed in mouse L fibroblasts, they were co-concentrated with ERM proteins at microvilli, whereas those lacking these clusters were diffusely distributed on the cell surface. The specific binding of ERM proteins to the juxta-membrane positively charged amino acid clusters of CD44, CD43, and ICAM-2 was confirmed by immunoprecipitation and site-directed mutagenesis. From these findings, we conclude that ERM proteins bind to integral membrane proteins bearing a positively charged amino acid cluster in their juxta-membrane cytoplasmic domain.