Differential functions of the two Src homology 2 domains in protein tyrosine phosphatase SH-PTP1.
SH-PTP1 (also known as PTP1C, HCP, and SHP) is a non-transmembrane protein tyrosine phosphatase (PTPase) containing two tandem Src homology 2 (SH2) domains. We show here that the two SH2 (N-SH2 and C-SH2) domains in SH-PTP1 have different functions in regulation of the PTPase domain and thereby signal transduction. While ... the N-terminal SH2 domain is both necessary and sufficient for autoinhibition through an intramolecular association with the PTPase domain, truncation of the C-SH2 domain [SH-PTP1 (delta CSH2) construct] has little effect on SH-PTP1 activity. A synthetic phosphotyrosine residue (pY) peptide derived from the erythropoietin receptor (EpoR pY429) binds to the N-SH2 domain and activates both wild-type SH-PTP1 and SH-PTP1 (delta CSH2) 60- to 80-fold. Another pY peptide corresponding to a phosphorylation site on the IgG Fc receptor (Fc gamma RIIB1 pY309) associates with both the C-SH2 domain (Kd = 2.8 microM and the N-SH2 domain (Kd = 15.0 microM) and also activates SH-PTP1 12-fold. By analysis of the effect of the Fc gamma RIIB1 pY309 peptide on SH-PTP1 (delta CSH2), SH-PTP1 (R30K/R33E), SH-PTP1 (R30K/R136K), and SH-PTP1 (R136K) mutants in which the function of either the N- or C-SH2 domain has been impaired, we have determined that both synthetic pY peptides stimulate SH-PTP1 by binding to its N-SH2 domain; binding of pY ligand to the C-SH2 domain has no effect on SH-PTP1 activity. We propose that the N-terminal SH2 domain serves both as a regulatory domain and as a recruiting unit, whereas the C-terminal SH2 domain acts merely as a recruiting unit.
Mesh Terms:
Amino Acid Sequence, Binding Sites, Cloning, Molecular, Enzyme Activation, Escherichia coli, Humans, Intracellular Signaling Peptides and Proteins, Kinetics, Models, Structural, Molecular Sequence Data, Protein Binding, Protein Tyrosine Phosphatase, Non-Receptor Type 11, Protein Tyrosine Phosphatase, Non-Receptor Type 6, Protein Tyrosine Phosphatases, Receptors, IgG, Recombinant Proteins, SH2 Domain-Containing Protein Tyrosine Phosphatases, Signal Transduction, src Homology Domains
Amino Acid Sequence, Binding Sites, Cloning, Molecular, Enzyme Activation, Escherichia coli, Humans, Intracellular Signaling Peptides and Proteins, Kinetics, Models, Structural, Molecular Sequence Data, Protein Binding, Protein Tyrosine Phosphatase, Non-Receptor Type 11, Protein Tyrosine Phosphatase, Non-Receptor Type 6, Protein Tyrosine Phosphatases, Receptors, IgG, Recombinant Proteins, SH2 Domain-Containing Protein Tyrosine Phosphatases, Signal Transduction, src Homology Domains
Proc. Natl. Acad. Sci. U.S.A.
Date: Feb. 06, 1996
PubMed ID: 8577729
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