Engineering NGF receptors to bind Grb2 directly uncovers differences in signaling ability between Grb2- and ShcA-binding sites.

Grb2 and ShcA are two phosphotyrosine-binding proteins that link receptor protein-tyrosine kinases to activation of the Ras-Erk pathway. While some receptors bind Grb2 directly, others bind ShcA, which provides a binding site for Grb2. In order to compare signal transduction through a Grb2-binding site with signal transduction through a ShcA-binding site, we replaced the ShcA-binding site in the NGF receptor with a Grb2-binding site. Our results show that the Grb2- and ShcA-binding sites have similar abilities to activate the Ras-Erk and PI 3-kinase-Akt pathways. In contrast, they displayed dramatic differences in their ability to activate DNA synthesis.