Localization of the Insulin-like Growth Factor I Receptor Binding Sites for the SH2 Domain Proteins p85, Syp, and GTPase Activating Protein

作者：B. Lynn Seely, Donna R. Reichart, Patricia A. Staubs, Byung Hak Jhun, David S. Hsu, Hiroshi Maegawa, Kim L. Milarski, Alan R. Saltiel, Jerrold M. Olefsky · 发表于：Journal of Biological Chemistry · 年份：1995 · DOI：10.1074/jbc.270.32.19151 · 被引用次数：66 · 研究领域：Growth Hormone and Insulin-like Growth Factors、PI3K/AKT/mTOR signaling in cancer、Thyroid Disorders and Treatments

Potential signaling substrates for the insulin-like growth factor I (IGF-I) receptor are SH2 domain proteins including the p85 subunit of phosphatidylinositol 3-kinase, the tyrosine phosphatase Syp, GTPase activating protein (GAP), and phospholipase C-gamma (PLC-gamma). In this study, we demonstrate an association between the IGF-I receptor and p85, Syp, and GAP, but not with PLC-gamma in lysates of cells overexpressing the human IGF-I receptor. We further investigated these interactions using glutathione S-transferase (GST) fusion proteins containing the amino-terminal SH2 domains of p85 or GAP, or both SH2 domains of Syp or PLC-gamma to precipitate the IGF-I receptor from purified receptor preparations and from whole cell lysates. p85-, Syp-, and GAP-GSTs precipitated the IGF-I receptor, whereas the PLC-gamma-GST did not. Using phosphopeptides corresponding to IGF-I receptor phosphorylation sites, we determined that the p85- and Syp-GST association with the IGF-I receptor could be inhibited by a carboxyl-terminal peptide containing pY1316 and that the GAP-GST association could be inhibited by a NPXY domain peptide. The GAP-GST binding site was confirmed by showing that a mutant IGF-I receptor with a deletion of the NPXY domain including tyrosine 950 was poorly precipitated by the GAP-GST. We conclude that p85 and Syp may bind directly to the IGF-I receptor at tyrosine 1316, and that GAP may bind to the IGF-I receptor at and PLC-gamma was not evident. p85, Syp, and GAP are p...