Heiska L, Alfthan K, Grönholm M, Vilja P, Vaheri A, Carpén O
Department of Pathology, University of Helsinki, Haartman Institute, 00014 Helsinki, Finland.
J Biol Chem. 1998 Aug 21;273(34):21893-900. doi: 10.1074/jbc.273.34.21893.
Ezrin is a cytoplasmic linker molecule between plasma membrane components and the actin-containing cytoskeleton. We studied whether ezrin is associated with intercellular adhesion molecule (ICAM)-1, -2, and -3. In transfected cells, ICAM-1 and ICAM-2 colocalized with ezrin in microvillar projections, whereas an ICAM-1 construct attached to cell membrane via a glycophosphatidylinositol anchor was uniformly distributed on the cell surface. An interaction of ICAM-2 and ezrin was seen by affinity precipitation, microtiter binding assay, coimmunoprecipitation, and surface plasmon resonance methods. The calculated KD value was 3.3 x 10(-7) M. Phosphatidylinositol 4, 5-bisphosphate (PtdIns(4,5)P2) induced an interaction of ezrin and ICAM-1 and enhanced the interaction of ezrin and ICAM-2, but ICAM-3 did not bind ezrin even in the presence of PtdIns(4,5)P2. PtdIns(4, 5)P2 was shown to bind to cytoplasmic tails of ICAM-1 and ICAM-2, which are the first adhesion proteins demonstrated to interact with PtdIns(4,5)P2. The results indicate an interaction of ezrin with ICAM-1 and ICAM-2 and suggest a regulatory role of phosphoinositide signaling pathways in regulation of ICAM-ezrin interaction.
埃兹蛋白是一种位于质膜成分与含肌动蛋白的细胞骨架之间的细胞质连接分子。我们研究了埃兹蛋白是否与细胞间黏附分子（ICAM）-1、-2和-3相关。在转染细胞中，ICAM-1和ICAM-2与埃兹蛋白在微绒毛突起中共定位，而通过糖基磷脂酰肌醇锚定附着于细胞膜的ICAM-1构建体在细胞表面均匀分布。通过亲和沉淀、微量滴定结合试验、共免疫沉淀和表面等离子体共振方法观察到ICAM-2与埃兹蛋白之间的相互作用。计算得到的KD值为3.3×10⁻⁷M。磷脂酰肌醇4,5-二磷酸（PtdIns(4,5)P2）诱导埃兹蛋白与ICAM-1相互作用，并增强埃兹蛋白与ICAM-2的相互作用，但即使在存在PtdIns(4,5)P2的情况下，ICAM-3也不与埃兹蛋白结合。已证明PtdIns(4,5)P2与ICAM-1和ICAM-2的细胞质尾巴结合，这是首次证明与PtdIns(4,5)P2相互作用的黏附蛋白。结果表明埃兹蛋白与ICAM-1和ICAM-2之间存在相互作用，并提示磷酸肌醇信号通路在调节ICAM-埃兹蛋白相互作用中起调节作用。
