Localization of the insulin-like growth factor I receptor binding sites for the SH2 domain proteins p85, Syp, and GTPase activating protein.
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 potential modulators of IGF-I receptor signal transduction.
Mesh Terms:
1-Phosphatidylinositol 3-Kinase, Amino Acid Sequence, Animals, Arsenicals, Binding Sites, CHO Cells, Cricetinae, GTPase-Activating Proteins, Insulin-Like Growth Factor I, Intracellular Signaling Peptides and Proteins, Molecular Sequence Data, Phosphorylation, Phosphotransferases (Alcohol Group Acceptor), Protein Tyrosine Phosphatase, Non-Receptor Type 1, Protein Tyrosine Phosphatase, Non-Receptor Type 11, Protein Tyrosine Phosphatase, Non-Receptor Type 6, Protein Tyrosine Phosphatases, Proteins, Receptor, IGF Type 1, SH2 Domain-Containing Protein Tyrosine Phosphatases, Type C Phospholipases, Tyrosine
1-Phosphatidylinositol 3-Kinase, Amino Acid Sequence, Animals, Arsenicals, Binding Sites, CHO Cells, Cricetinae, GTPase-Activating Proteins, Insulin-Like Growth Factor I, Intracellular Signaling Peptides and Proteins, Molecular Sequence Data, Phosphorylation, Phosphotransferases (Alcohol Group Acceptor), Protein Tyrosine Phosphatase, Non-Receptor Type 1, Protein Tyrosine Phosphatase, Non-Receptor Type 11, Protein Tyrosine Phosphatase, Non-Receptor Type 6, Protein Tyrosine Phosphatases, Proteins, Receptor, IGF Type 1, SH2 Domain-Containing Protein Tyrosine Phosphatases, Type C Phospholipases, Tyrosine
J. Biol. Chem.
Date: Aug. 11, 1995
PubMed ID: 7642582
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