NON-SH2 DOMAINS WITHIN INSULIN-RECEPTOR SUBSTRATE-1 AND SHC MEDIATE THEIR PHOSPHOTYROSINE-DEPENDENT INTERACTION WITH THE NPEY MOTIF OF THE INSULIN-LIKE GROWTH-FACTOR-I RECEPTOR

Insulin receptor substrate-1 (IRS-1) and SHC become rapidly phosphoryl ated upon tyrosines after insulin-like growth factor I receptor (IGFIR ) activation. In this study we demonstrate that IRS-1, SHC, and the p8 5 sub unit of phosphatidylinositol 3-kinase interact directly and spec ifically with the IGFIR. The interaction of all three proteins is depe ndent upon IGFIR kinase activity and, furthermore, substitution of Tyr -950 with Phe within the NPEY motif of the IGFIR eliminated interactio n with both SHC and IRS-1 but had no effect upon p85 interaction. We s how that residues 160-516 of IRS-1 and 1-238 of SHC are sufficient and necessary for receptor interaction in the yeast two-hybrid assay. We also demonstrate a direct in vitro interaction between the IGFIR and a fusion protein containing SHC amino acids 1-238. No interaction was o bserved with a SHC protein containing only the SH2 domain. We conclude that SHC and IRS-1 interact with the tyrosine-phosphorylated NPEY mot if of the IGFIR, and that both proteins interact via related motifs lo cated in their amino termini. We conclude that the interactions of SHC and IRS-1 with the IGFIR are similar to those which we have previousl y defined with the insulin receptor.