Specificity of the PTB Domain of Shc for Turn-forming Pentapeptide Motifs Amino-terminal to Phosphotyrosine

Specificity of the PTB Domain of Shc for Turn-forming Pentapeptide Motifs Amino-terminal to Phosphotyrosine

Shc phosphorylation in cells following growth factor, insulin, cytokine, and lymphocyte receptor activation leads to its association with Grb2 and activation of Ras. In addition to being a cytoplasmic substrate of tyrosine kinases, Shc contains an SH2 domain and a non-SH2 phosphotyrosine binding (PT...

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Bibliographic Details
Published in:The Journal of biological chemistry Vol. 270; no. 31; p. 18205
Main Authors: Thomas Trb, Wonjae E. Choi, Gert Wolf, Elizabeth Ottinger, YunJun Chen, Michael Weiss, Steven E. Shoelson
Format: Journal Article
Language:English
Published: American Society for Biochemistry and Molecular Biology 04-08-1995
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Summary:Shc phosphorylation in cells following growth factor, insulin, cytokine, and lymphocyte receptor activation leads to its association with Grb2 and activation of Ras. In addition to being a cytoplasmic substrate of tyrosine kinases, Shc contains an SH2 domain and a non-SH2 phosphotyrosine binding (PTB) domain. Here we show that the Shc PTB domain, but not the SH2 domain, binds with high affinity (ID ≅ 1 μM) to phosphopeptides corresponding to the sequence surrounding Tyr of the polyoma virus middle T (mT) antigen (LLSNPTpYSVMRSK). Truncation studies show that five residues amino-terminal to tyrosine are required for high affinity binding, whereas all residues carboxyl-terminal to tyrosine can be deleted without loss of affinity. Substitution studies show that tyrosine phosphorylation is required and residues at −5, −3, −2, and −1 positions relative to pTyr are important for this interaction. 1 H NMR studies demonstrate that the phosphorylated mT antigen-derived sequence forms a stable β turn in solution, and correlations between structure and function indicate that the β turn is important for PTB domain recognition. These results show that PTB domains are functionally distinct from SH2 domains. Whereas SH2 domain binding specificity derives from peptide sequences carboxyl-terminal to phosphotyrosine, the Shc PTB domain gains specificity by interacting with β turn-forming sequences amino-terminal to phosphotyrosine.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.270.31.18205