TY - JOUR
T1 - Insulin and epidermal growth factor receptors regulate distinct pools of Grb2-SOS in the control of Ras activation
AU - Waters, Steven B.
AU - Chen, Dong
AU - Kao, Aimee W.
AU - Okada, Shuichi
AU - Holt, Kathleen H.
AU - Pessin, Jeffrey E.
PY - 1996
Y1 - 1996
N2 - Insulin and epidermal growth factor (EGF) stimulate a rapid but transient increase in the amount of GTP bound to Ras that returns to the basal GDP-bound state within 10-30 min. Although insulin stimulation resulted in a dissociation of the Grb2·SOS complex, EGF did not affect the Grb2·SOS complex but instead induced dissociation of Grb2-SOS from tyrosine- phosphorylated Shc. The dissociation of Grb2-SOS from Shc was not due to dephosphorylation as Shc remained persistently tyrosine-phosphorylated during this time. Furthermore, there was no decrease in the extent of insulin receptor substrate 1, insulin receptor, or EGF receptor tyrosine phosphorylation. Surprisingly, however, despite the EGF-induced decrease in the amount of Grb2-SOS bound to Shc, the extent of Grb2 associated with Shc remained constant, and there was a concomitant increase in the amount of SOS associated with Grb2. In addition, after the insulin-stimulated dissociation of Grb2 from SOS, EGF treatment induced the reassociation of the Grb2·SOS complex. Quantitative immunoprecipitation demonstrated that only a small fraction of the total cellular pool of Grb2 was associated with SOS. Similarly, only a small fraction of SOS and Grb2 were co-immunoprecipitated with Shc. Together, these data suggest the presence of distinct Grb2-SOS pools that are independently utilized by insulin and EGF in their recruitment to tyrosine-phosphorylated Shc.
AB - Insulin and epidermal growth factor (EGF) stimulate a rapid but transient increase in the amount of GTP bound to Ras that returns to the basal GDP-bound state within 10-30 min. Although insulin stimulation resulted in a dissociation of the Grb2·SOS complex, EGF did not affect the Grb2·SOS complex but instead induced dissociation of Grb2-SOS from tyrosine- phosphorylated Shc. The dissociation of Grb2-SOS from Shc was not due to dephosphorylation as Shc remained persistently tyrosine-phosphorylated during this time. Furthermore, there was no decrease in the extent of insulin receptor substrate 1, insulin receptor, or EGF receptor tyrosine phosphorylation. Surprisingly, however, despite the EGF-induced decrease in the amount of Grb2-SOS bound to Shc, the extent of Grb2 associated with Shc remained constant, and there was a concomitant increase in the amount of SOS associated with Grb2. In addition, after the insulin-stimulated dissociation of Grb2 from SOS, EGF treatment induced the reassociation of the Grb2·SOS complex. Quantitative immunoprecipitation demonstrated that only a small fraction of the total cellular pool of Grb2 was associated with SOS. Similarly, only a small fraction of SOS and Grb2 were co-immunoprecipitated with Shc. Together, these data suggest the presence of distinct Grb2-SOS pools that are independently utilized by insulin and EGF in their recruitment to tyrosine-phosphorylated Shc.
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U2 - 10.1074/jbc.271.30.18224
DO - 10.1074/jbc.271.30.18224
M3 - Article
C2 - 8663461
AN - SCOPUS:0029896368
SN - 0021-9258
VL - 271
SP - 18224
EP - 18230
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 30
ER -