Thuillier L, Hivroz C, Fagard R, Andreoli C, Mangeat P
INSERM-U132, Hôpital Necker-Enfants Malades, Paris, France.
Cell Immunol. 1994 Jul;156(2):322-31. doi: 10.1006/cimm.1994.1178.
Ezrin is a cytoskeletal protein which is tyrosine phosphorylated in human T lymphocytes upon stimulation through CD3 antigen (Egerton, M., Burgess, W., Chen, D., Druker, B. J., Bretscher, A., and Samelson, L. A., J. Immunol. 149, 1847, 1992). We found that tyrosine phosphorylation of ezrin was markedly enhanced by ligation of either CD3 or CD4 antigen and peaked between 1 and 2 min. Furthermore, stimulations through CD4 and CD3 antigens were additive. Using the cell line HUT 78 T transfected with either normal human CD4 or mutated CD4 molecules unable to associate with p56lck tyrosine kinase, we showed that this kinase plays a major role in the tyrosine phosphorylation of ezrin. Moreover, CD45R ligation studies provided evidence that the membrane-associated tyrosine phosphatase CD45 activity regulates ezrin tyrosine phosphorylation. Subcellular fractionation showed that although ezrin is mainly located in the cytosol of T cells, anti-CD4-induced ezrin phosphorylation involved the membrane fraction, with no concomitant translocation of the protein from the cytosol to the membrane.
埃兹蛋白是一种细胞骨架蛋白，在人T淋巴细胞中，通过CD3抗原刺激后会发生酪氨酸磷酸化（埃杰顿，M.，伯吉斯，W.，陈，D.，德鲁克，B. J.，布雷切尔，A.，以及萨梅尔森，L. A.，《免疫学杂志》149，1847，1992）。我们发现，通过CD3或CD4抗原的连接，埃兹蛋白的酪氨酸磷酸化显著增强，并在1至2分钟之间达到峰值。此外，通过CD4和CD3抗原的刺激具有累加效应。利用转染了正常人CD4或无法与p56lck酪氨酸激酶结合的突变型CD4分子的HUT 78 T细胞系，我们表明该激酶在埃兹蛋白的酪氨酸磷酸化中起主要作用。此外，CD45R连接研究提供了证据，表明膜相关酪氨酸磷酸酶CD45的活性调节埃兹蛋白的酪氨酸磷酸化。亚细胞分级分离显示，尽管埃兹蛋白主要位于T细胞的胞质溶胶中，但抗CD4诱导的埃兹蛋白磷酸化涉及膜部分，且该蛋白并未伴随从胞质溶胶向膜的转运。
