The shc gene encodes three widely expressed proteins of 46, 52 and 66
kDa. Overexpression of p46shc and p52shc in NIH3T3 fibroblasts induces
a tumorigenic phenotype. Shc products are phosphorylated on tyrosine
by the activated epidermal growth factor receptor (EGFR) and become ph
ysically associated with EGFR via their SH2 domain. Thus Shc oncoprote
ins may play a role in mitogenic signal transduction. Here we report t
hat Shc products are substrates also of the erbB-2 kinase and form com
plexes with the erbB-2 product in intact cells. In vitro, the bacteria
lly expressed Shc SH2 domain is sufficient to reconstitute the high af
finity Shc/erbB-2 interaction. The erbB-2 region required for Shc bind
ing was narrowed down to the most COOH-terminal 179 residues of gp185e
rbB-2; within this region, phosphorylation of one or more of the erbB-
2 autophosphorylation sites is required for Shc/gp185erbB-2 complex fo
rmation as well as optimal phosphorylation of Shc products by the erbB
-2 kinase. Thus, Shc proteins may play a role in signal transduction b
y gp185erbB-2.