This phosphotyrosil peptide sequence is derived from the autophosphorylation site (Tyr992) of epidermal growth factor receptor (EGFR 988-993). Using synthetic pTyr-containing peptides that correspond to natural phosphorylation sites in proteins, several groups have demonstrated that PTPases display a range of kcat/Km values for these relatively short peptide substrates. This peptide is a minimal (6 residues) peptide substrate for both the Yersinia PTPase and the mammalian PTP1. It is often complexed with the catalytically inactive protein-tyrosine phosphate 1B (PTP1B).