Ostergaard H L, Trowbridge I S
Department of Cancer Biology, Salk Institute, San Diego, California 92138.
J Exp Med. 1990 Jul 1;172(1):347-50. doi: 10.1084/jem.172.1.347.
Antibody-mediated CD4 crosslinking results in increased tyrosine phosphorylation and tyrosine kinase activity of the associated p56lck. Treatment with anti-CD4 and anti-Ig also induced the phosphorylation of p56lck in a CD45- mutant cell line, indicating that the increase in phosphotyrosine content of p56lck is not the result of being sequestered from CD45 protein tyrosine phosphatase (PTPase). Antibody-mediated coclustering of CD45 with CD4 inhibited the anti-CD4-induced phosphorylation of p56lck on tyrosine and the concomitant increase in in vitro kinase activity. Similar results were obtained when CD45 was coclustered with CD8 on cytotoxic T cell lines. These observations provide strong evidence that p56lck is a substrate for CD45 in vivo and provide an assay to study the regulation and specificity of CD45 PTPase activity.
抗体介导的CD4交联导致相关的p56lck酪氨酸磷酸化增加以及酪氨酸激酶活性增强。用抗CD4和抗Ig处理也能在CD45 -突变细胞系中诱导p56lck的磷酸化,这表明p56lck磷酸酪氨酸含量的增加并非是被CD45蛋白酪氨酸磷酸酶(PTPase)隔离的结果。抗体介导的CD45与CD4共聚集抑制了抗CD4诱导的p56lck酪氨酸磷酸化以及体外激酶活性随之增加。当CD45与细胞毒性T细胞系上的CD8共聚集时也得到了类似结果。这些观察结果提供了有力证据,表明p56lck在体内是CD45的底物,并提供了一种研究CD45 PTPase活性调控及特异性的检测方法。