Activation-induced association of a 145-kDa tyrosine-phosphorylated protein with Shc and Syk in B lymphocytes and macrophages
Activation-induced association of a 145-kDa tyrosine-phosphorylated protein with Shc and Syk in B lymphocytes and macrophages
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DOI：
10.1074/jbc.271.2.1145
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发表时间：
1996-01-12
影响因子：
4.8
通讯作者：
DeFranco, AL
中科院分区：
文献类型：
--
作者：
Crowley, MT;Harmer, SL;DeFranco, AL
许多细胞表面受体的结合导致一组重叠的蛋白质底物的酪氨酸磷酸化。一些蛋白质，如接头蛋白Shc和经常观察到的Shc相关蛋白p145，是各种受体信号通路的共同底物，因此特别令人感兴趣。B细胞经B细胞抗原受体(BCR)或白介素4(IL-4)受体活化后，巨噬细胞经脂多糖(LPS)或免疫球蛋白G铁受体(Fc-Gamma R)交联后，酪氨酸磷酸化Shc和p145与抗Shc抗体共沉淀。在BCR刺激的情况下，我们已经证明这代表了可诱导复合体的形成。此外，在巨噬细胞的内毒素激活或Fc-Gamma R交联物和B细胞的BCR交联物(但不是IL-4处理)的反应中，我们观察到与酪氨酸激酶Syk相关的类似的酪氨酸磷酸化的p145蛋白。我们没有检测到任何与Syk相关的Shc，这表明没有大量形成Shc、Syk和p145的三分子复合体。根据几个标准，Syk相关的p145很可能与先前发现的Shc相关的p145蛋白相同。与Syk相关的p145和与Shc相关的p145在SDS-聚丙烯酰胺凝胶电泳中显示出相同的迁移率和诱导酪氨酸磷酸化的相同模式。与Shc或Syk共沉淀的p145蛋白与GST-Shc融合蛋白结合。此外，一种针对Shc相关p145的单抗也免疫印迹了Syk相关p145。观察到p145与Shc和Syk蛋白有关，对多种受体的刺激做出反应，表明它在协调早期信号事件中发挥着重要作用。
Engagement of many cell surface receptors results in tyrosine phosphorylation of an overlapping set of protein substrates. Some proteins, such as the adaptor protein Shc and a frequently observed Shc-associated protein, p145, are common substrates in a variety of receptor signaling pathways and are thus of special interest. Tyrosine-phosphorylated Shc and p145 coprecipitated with anti-Shc antibodies following B cell antigen receptor (BCR) cross-linking or interleukin-4 (IL-4) receptor activation in B cells, and after lipopolysaccharide (LPS) treatment or IgG Fe receptor (Fc gamma R) crosslinking in macrophages. In the case of BCR stimulation, we have shown that this represented the formation of an inducible complex. Furthermore, in response to LPS activation or Fc gamma R cross-linking of macrophages and BCR cross-linking (but not IL-4 treatment) of B cells, we observed a similar tyrosine-phosphorylated p145 protein associated with the tyrosine kinase Syk. We did not detect any Shc-associated with Syk, indicating that a trimolecular complex of Shc, Syk, and p145 was not formed in significant amounts. By several criteria, the Syk-associated p145 was very likely the same protein as the previously identified Shc-associated p145. The Syk-associated p145 and the Shc-associated p145 exhibited identical mobility by SDS-polyacrylamide gel electrophoresis and identical patterns of induced tyrosine phosphorylation. The p145 protein that coprecipitated with either Shc or Syk bound to a GST-Shc fusion protein. In addition, a monoclonal antibody developed against Shc-associated p145 also immunoblotted the Syk-associated p145. The observations that p145 associated with both Shc and Syk proteins, in response to stimulation of a variety of receptors, suggest that it plays an important role in coordinating early signaling events.