Nel A E, Gupta S, Lee L, Ledbetter J A, Kanner S B
Department of Medicine, UCLA School of Medicine 90024, USA.
J Biol Chem. 1995 Aug 4;270(31):18428-36. doi: 10.1074/jbc.270.31.18428.
Signaling by the T-cell antigen receptor (TCR) involves both phospholipase C (PLC)-gamma 1 and p21ras activation. While failing to induce Shc/Grb2 association, ligation of the TCR/CD3 receptor in Jurkat T-cells induced hSos1-Grb2 complexes. In addition to hSos1, Grb2 participates in the formation of a tyrosine phosphoprotein complex that includes 145-, 95-, 70-, 54-, and 36-38-kDa proteins. p145 was identified as PLC-gamma 1 and p70 as the protein tyrosine kinase, ZAP-70. Although of the same molecular weight, p95 was not recognized by an anti-serum to p95 Vav. The SH2 domains of Grb2 and PLC-gamma 1 were required for the formation of this protein complex. In anti-CD3-treated cells, Grb2 redistributed from the cytosol to a particulate cell compartment along with p36/p38, ZAP-70, and PLC-gamma 1. Part of the Grb2 complex associated with the particulate compartment could be extracted with Nonidet P-40, while the rest was Nonidet P-40 insoluble. In both the detergent-soluble and -insoluble fractions, Grb2 coimmunoprecipitated with the zeta-chain of the TCR. Taken together, these results indicate that anti-CD3 induces Grb2-hSos1-PLC-gamma 1-p36/p38-ZAP70 complexes, which localize in the vicinity of TCR-zeta.
T细胞抗原受体（TCR）信号传导涉及磷脂酶C（PLC）-γ1和p21ras激活。虽然不能诱导Shc/Grb2结合，但在Jurkat T细胞中TCR/CD3受体的连接诱导了hSos1-Grb2复合物的形成。除了hSos1，Grb2还参与形成一种酪氨酸磷酸化蛋白复合物，该复合物包括145 kDa、95 kDa、70 kDa、54 kDa和36 - 38 kDa的蛋白质。p145被鉴定为PLC-γ1，p70被鉴定为蛋白酪氨酸激酶ZAP-70。尽管分子量相同，但抗p95 Vav血清不能识别p95。Grb2和PLC-γ1的SH2结构域是形成这种蛋白质复合物所必需的。在抗CD3处理的细胞中，Grb2与p36/p38、ZAP-70和PLC-γ1一起从胞质溶胶重新分布到颗粒状细胞区室。与颗粒状区室相关的部分Grb2复合物可以用Nonidet P-40提取，而其余部分不溶于Nonidet P-40。在去污剂可溶和不可溶部分中，Grb2都与TCR的ζ链共免疫沉淀。综上所述，这些结果表明抗CD3诱导了Grb2-hSos1-PLC-γ1-p36/p38-ZAP70复合物，其定位于TCR-ζ附近。
