Ricci A, Lanfrancone L, Chiari R, Belardo G, Pertica C, Natali P G, Pelicci P G, Segatto O
Laboratory of Immunology, Regina Elena Cancer Institute, Roma, Italy.
Oncogene. 1995 Oct 19;11(8):1519-29.
In murine fibroblasts activation of the Shc/Grb-2 pathway by the ErbB-2 kinase involves tyrosine phosphorylation of Shc products and the formation of Shc/ErbB-2, Shc/Grb-2 and Grb-2/ErbB-2 complexes. Tyr 1139 of ErbB-2 bound to the Grb-2 SH2 domain in vitro as well as in intact cells. Tyr 1221 and 1248 are binding sites of gp185ErbB-2 for Shc SH2 domain in vitro whereas Tyr 1196 and 1248 are major binding sites of ErbB-2 for Shc PTB domain. Inhibition of Shc/ErbB-2 complex formation in intact cells was obtained by simultaneous mutational inactivation of Shc SH2 and Shc PTB binding sites of gp185ErbB-2. Shc/ErbB-2 complexes are formed upon activation of the ErbB-2 kinase and tyrosine phosphorylation of Shc proteins; they are located in both cytosol and cellular membranes. ErbB-2 activation induces also translocation of Grb-2 from cytosol to membranes. This network of protein-protein interactions may reflect the ability of the Shc/Grb-2 pathway to act as a molecular switch controlling different cellular functions regulated by RTK activation. In fact the Ras GDP exchanger mSOS was recruited in Grb-2/ErbB-2 complexes; furthermore besides mSOS, other polypeptides present in either cytosolic or membrane preparations were able to complex in vitro with Grb-2 SH3 domains.
在鼠成纤维细胞中，ErbB-2激酶对Shc/Grb-2途径的激活涉及Shc产物的酪氨酸磷酸化以及Shc/ErbB-2、Shc/Grb-2和Grb-2/ErbB-2复合物的形成。在体外以及完整细胞中，与Grb-2 SH2结构域结合的ErbB-2的Tyr 1139。Tyr 1221和1248在体外是gp185ErbB-2与Shc SH2结构域的结合位点，而Tyr 1196和1248是ErbB-2与Shc PTB结构域的主要结合位点。通过同时使gp185ErbB-2的Shc SH2和Shc PTB结合位点发生突变失活，在完整细胞中抑制了Shc/ErbB-2复合物的形成。Shc/ErbB-2复合物在ErbB-2激酶激活和Shc蛋白酪氨酸磷酸化后形成；它们位于细胞质和细胞膜中。ErbB-2激活还诱导Grb-2从细胞质转运到细胞膜。这种蛋白质-蛋白质相互作用网络可能反映了Shc/Grb-2途径作为分子开关控制由RTK激活调节不同细胞功能的能力。事实上，Ras GDP交换蛋白mSOS被招募到Grb-2/ErbB-2复合物中；此外，除了mSOS，存在于细胞质或膜制剂中的其他多肽能够在体外与Grb-2 SH3结构域结合。
