title: Differential functions of the two Src homology 2 domains in protein tyrosine phosphatase SH-PTP1.
abstract: 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.
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: D
authors.initials: D
authors.lastname: Pei
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: C T
authors.initials: CT
authors.lastname: Walsh
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D004789:Enzyme Activation; D004926:Escherichia coli; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D008961:Models, Structural; D008969:Molecular Sequence Data; D011485:Protein Binding; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D017452:Receptors, IgG / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D015398:Signal Transduction; D018909:src Homology Domains
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D017452:Receptors, IgG; D011994:Recombinant Proteins; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases