IndraLab
Statements
"We have shown previously that amino acid residues flanking the phosphotyrosine are important for efficient PTP1 catalysis (Table 1 and Refs. 9, 10, and 17). For example, the kcat/Km value for the undecapeptide, EGFR988-989 (epidermal growth factor autophosphorylation site Tyr992, residues 988-998) (Asp-Ala-Asp-Glu-pTyr-Leu-Ile-Pro-Gln-Gln-Gly) is 3220-fold higher than that of phosphotyrosine (Table 1). We further demonstrated that a minimum of six amino acid residues are required for the most efficient PTP1 binding and catalysis."
"Given that substrate trapping occurred in intact cells and that the interaction was very specific, it is highly likely that egfr and gab1 represent physiological shp2 substrates.To further confirm that phosphotyrosyl proteins trapped by SHP2 are target substrates, we carried out an immunocomplex in vitrophosphatase assay.The WT protein partially dephosphorylated both the EGFR and Gab1, whereas the DM protein did not"
"EGFR possesses three major and two minor tyrosine autophosphorylation sites located at Y1068, Y1148, Y1173, and at Y992 and Y1086 respectively. In addition, EGFR Y1114 is preceded by glutamic acid (Figure 1), which should be preferred by the EGFR kinase as indicated in previous work"
"Inhibition is achieved through the dephosphorylation of RasGAP binding sites at the level of the plasma membrane. We have identified Tyr992 of the epidermal growth factor receptor (EGFR) to be one such site, since its mutation to Phe renders the EGFR refractory to the effect of dominant-negative SHP2. To our knowledge, this is the first report to outline the site and molecular mechanism of action of SHP2 in EGFR signaling,"
"We found that EGF receptor (EGFR) was a direct substrate of VHR and that overexpression of VHR down-regulated EGFR phosphorylation, particularly at Tyr-992 residue. Expression of VHR inhibited the activation of phospholipase Cγ and protein kinase C, both downstream effectors of Tyr-992 phosphorylation of EGFR."