PTB Domains of IRS-1 and Shc Have Distinct but Overlapping Binding Specificities

• Published in: The Journal of biological chemistry 1995-11, Vol.270 (46), p.27407-27410
• Main Authors: Wolf, G, Trüb, T, Ottinger, E, Groninga, L, Lynch, A, White, M F, Miyazaki, M, Lee, J, Shoelson, S E
• Format: Article
• Language: English
• Subjects: 3T3 Cells; Amino Acid Sequence; Animals; Binding Sites; Binding, Competitive; Cloning, Molecular; Escherichia coli; Humans; Insulin Receptor Substrate Proteins; Kinetics; Mice; Molecular Sequence Data; Phosphopeptides - chemistry; Phosphopeptides - pharmacology; Phosphoproteins - chemistry; Phosphoproteins - metabolism; Polymerase Chain Reaction; Receptor, Insulin - biosynthesis; Receptor, Insulin - metabolism; Recombinant Proteins - biosynthesis; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Sequence Homology, Amino Acid; Substrate Specificity; Transfection; Tyrosine
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.270.46.27407

PTB domains are non-Src homology 2 (SH2) phosphotyrosine binding domains originally described in the receptor tyrosine kinase substrate, Shc. By serial truncation, we show that a 174-residue region of Shc p52 (33-206) has full PTB activity. We also show that a 173-residue region of insulin receptor substrate-1 (IRS-1; residues 144-316) has related PTB activity. In vitro both domains bind directly to activated insulin receptors. Binding is abrogated by substitution of Tyr-960 and selectively inhibited by phosphopeptides containing NP X Y sequences. Phosphopeptide assays developed to compare PTB domain specificities show that the Shc PTB domain binds with highest affinity to X Nβ β pY motifs derived from middle T (mT), TrkA, ErbB4, or epidermal growth factor receptors ( = hydrophobic, β = β-turn forming); the IRS-1 PTB domain does not bind with this motif. In contrast, both the Shc and IRS-1 PTB domains bind XX Nβ β pY sequences derived from insulin and interleukin 4 receptors, although specificities vary in detail. Shc and IRS-1 are phosphorylated by distinct but overlapping sets of receptor-linked tyrosine kinases. These differences may be accounted for by the inherent specificities of their respective PTB domains.