In vivo association of v-Abl with Shc mediated by a non-phosphotyrosine-dependent SH2 interaction.
A necessary downstream element of Abelson murine leukemia virus (Ab-MLV)-mediated transformation is Ras, which can be activated by the phosphotyrosine-dependent association of Shc with the Grb2-mSos complex. Here we show that Shc is tyrosine-phosphorylated and associates with Grb2 in v-Abl-transformed cells, whereas Shc in NIH3T3 cells is phosphorylated solely on serine and is not Grb2-associated. In addition, Shc coprecipitates with P120 v-Abl and P70 v-Abl, which lacks the carboxyl terminus. Surprisingly, a kinase-defective mutant of P120 also binds Shc, demonstrating that Shc/v-Abl association is a phosphotyrosine-independent interaction. Glutathione S-transferase fusion proteins were used to map the interacting domains and showed that Shc from both NIH3T3 and v-Abl-transformed cells binds to the Abl SH2 domain and that P120 v-Abl binds to a region in the amino terminus of Shc. Consistent with these data, a v-Abl mutant encoding only the Gag and SH2 regions was able to bind Shc in vivo. The unique non-phosphotyrosine-mediated binding of Shc may allow direct tyrosine phosphorylation of Shc by v-Abl and subsequent activation of the Ras pathway through assembly of a signaling complex with Grb2-mSos.
Raffel
G D
GD
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
Parmar
K
K
Rosenberg
N
N
D016475:3T3 Cells; D000011:Abelson murine leukemia virus / Q000235:genetics*; D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D002461:Cell Line, Transformed; D016313:Genes, abl; D008024:Ligands; D051379:Mice; D016374:Oncogene Proteins v-abl / Q000302:isolation & purification / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D010750:Phosphoproteins / Q000302:isolation & purification / Q000378:metabolism; D019000:Phosphotyrosine; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D018909:src Homology Domains
D008024:Ligands; D016374:Oncogene Proteins v-abl; D010710:Phosphates; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D019000:Phosphotyrosine