Dissecting the interaction of SHP-2 with PZR, an immunoglobulin family protein containing immunoreceptor tyrosine-based inhibitory motifs.
Tyrosine phosphorylation of membrane proteins plays a crucial role in cell signaling by recruiting Src homology 2 (SH2) domain-containing signaling molecules. Recently, we have isolated a transmembrane protein designated PZR that specifically binds tyrosine phosphatase SHP-2, which has two SH2 domains (Zhao, Z. J., and Zhao, R. (1998) J. Biol. Chem. 273, 29367-29372). PZR belongs to the immunoglobulin superfamily. Its intracellular segment contains four putative sites of tyrosine phosphorylation. By site-specific mutagenesis, we found that the tyrosine 241 and 263 embedded in the consensus immunoreceptor tyrosine-based inhibitory motifs VIYAQL and VVYADI, respectively, accounted for the entire tyrosine phosphorylation of PZR. The interaction between PZR and SHP-2 requires involvement of both tyrosyl residues of the former and both SH2 domains of the latter, since its was disrupted by mutating a single tyrosyl residue or an SH2 domain. Overexpression of catalytically inactive but not active forms of SHP-2 bearing intact SH2 domains in cells caused hyperphosphorylation of PZR. In vitro, tyrosine-phosphorylated PZR was efficiently dephosphorylated by the full-length form of SHP-2 but not by its SH2 domain-truncated form. Together, the data indicate that PZR serves not only as a specific anchor protein of SHP-2 on the plasma membrane but also as a physiological substrate of the enzyme. The coexisting binding and dephosphorylation of PZR by SHP-2 may function to terminate signal transduction initiated by PZR and SHP-2 and to set a threshold for the signal transduction to be initiated.
Zhao
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Division of Hematology/Oncology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University, Nashville, Tennessee 37232-6305, USA.
Zhao
Z J
ZJ
D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism*; D002384:Catalysis; D002460:Cell Line; D003545:Cysteine / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D019169:Jurkat Cells; D008956:Models, Chemical; D016297:Mutagenesis, Site-Directed; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D012694:Serine / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D018909:src Homology Domains
D002352:Carrier Proteins; D018076:DNA, Complementary; D047908:Intracellular Signaling Peptides and Proteins; C115628:MPZL1 protein, human; D010750:Phosphoproteins; D014443:Tyrosine; D012694:Serine; 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; D003545:Cysteine