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

1995; Elsevier BV; Volume: 270; Issue: 46 Linguagem: Inglês

10.1074/jbc.270.46.27407

1083-351X

G. Wolf, Thomas Trüb, Elizabeth A. Ottinger, Lori Groninga, Ann Lynch, Morris F. White, Masaya Miyazaki, Jongsoon Lee, Steven E. Shoelson,

Protein Kinase Regulation and GTPase Signaling

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 Ψ X Nβ 1 β 2 pY motifs derived from middle T (mT), TrkA, ErbB4, or epidermal growth factor receptors (Ψ = 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 ΨΨΨ XX Nβ 1 β 2 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.