Expression, purification, and characterization of SH2-containing protein tyrosine phosphatase, SH-PTP2

J Biol Chem. 1993 Oct 25;268(30):22771-6.


A human protein tyrosine phosphatase containing two src homology 2 (SH2) domains (SH-PTP2) was expressed in Escherichia coli under T7 promoter control and purified to near homogeneity. The purified protein, with molecular mass of 68 kDa on SDS-polyacrylamide gel electrophoresis, was identified as SH-PTP2 by its protein tyrosine phosphatase activity and N-terminal amino acid sequence analysis. Its protein tyrosine phosphatase activity was sensitive to pH and salt concentration. Whereas its optimum pH for the low molecular weight substrate para-nitrophenyl phosphate is 5.6, the pH optima for peptide substrates were shifted toward neutral. With the artificial protein substrate reduced, carboxyamidomethylated, and maleylated lysozyme, it displays 2000-fold lower Km (1.7 microM) and 2.4-fold higher kcat (0.11 s-1) than with para-nitrophenyl phosphate. Among the phosphopeptides from autophosphorylation sites of receptors for epidermal growth factor and platelet-derived growth factor, SH-PTP2 displayed high activity toward phosphopeptides corresponding to pY992 of the epidermal growth factor receptor and pY1009 and pY1021 of the platelet-derived growth factor receptor. In further enzymatic studies with phosphopeptides corresponding to pY1009, SH-PTP2 showed nonlinear Line-weaver-Burk double-reciprocal plots, suggesting that the phosphopeptide corresponding to pY1009 may have a substrate and allosteric effect.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Chromatography, Ion Exchange
  • Cloning, Molecular
  • Electrophoresis, Polyacrylamide Gel
  • ErbB Receptors / metabolism
  • Escherichia coli
  • Humans
  • Hydrogen-Ion Concentration
  • Kinetics
  • Molecular Sequence Data
  • Molecular Weight
  • Peptide Fragments / isolation & purification
  • Phosphopeptides / metabolism
  • Protein Tyrosine Phosphatases / biosynthesis
  • Protein Tyrosine Phosphatases / isolation & purification
  • Protein Tyrosine Phosphatases / metabolism*
  • Receptors, Platelet-Derived Growth Factor / metabolism
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Substrate Specificity
  • Thermodynamics


  • Peptide Fragments
  • Phosphopeptides
  • Recombinant Proteins
  • ErbB Receptors
  • Receptors, Platelet-Derived Growth Factor
  • Protein Tyrosine Phosphatases