Multiple interactions between receptor protein-tyrosine phosphatase (RPTP) alpha and membrane-distal protein-tyrosine phosphatase domains of various RPTPs.
Receptor protein-tyrosine phosphatase (RPTP) alpha belongs to the large family of receptor protein-tyrosine phosphatases containing two tandem phosphatase domains. Most of the catalytic activity is retained in the first, membrane-proximal domain (RPTPalpha-D1), and little is known about the function of the second, membrane-distal domain (RPTPalpha-D2). We investigated whether proteins bound to RPTPalpha using the two-hybrid system and found that the second domain of RPTPsigma interacted with the juxtamembrane domain of RPTPalpha. We confirmed this interaction by co-immunoprecipitation experiments. Furthermore, RPTPalpha not only interacted with RPTPsigma-D2 but also with RPTPalpha-D2, LAR-D2, RPTPdelta-D2, and RPTPmu-D2, members of various RPTP subfamilies, although with different affinities. In the yeast two-hybrid system and in glutathione S-transferase pull-down assays, we show that the RPTP-D2s interacted directly with the wedge structure of RPTPalpha-D1 that has been demonstrated to be involved in inactivation of the RPTPalpha-D1/RPTPalpha-D1 homodimer. The interaction was specific because the equivalent wedge structure in LAR was unable to interact with RPTPalpha-D2 or LAR-D2. In vivo, we show that other interaction sites exist as well, including the C terminus of RPTPalpha-D2. The observation that RPTPalpha, but not LAR, bound to multiple RPTP-D2s with varying affinities suggests a specific mechanism of cross-talk between RPTPs that may regulate their biological function.
Blanchetot
C
C
Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands.
den Hertog
J
J
D000818:Animals; D019556:COS Cells; D002460:Cell Line; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D009419:Nerve Tissue Proteins / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D054623:Receptor-Like Protein Tyrosine Phosphatases, Class 2; D054630:Receptor-Like Protein Tyrosine Phosphatases, Class 4; D054633:Receptor-Like Protein Tyrosine Phosphatases, Class 5; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection; D020798:Two-Hybrid System Techniques
D009419:Nerve Tissue Proteins; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D005982:Glutathione Transferase; C516841:PTPRA protein, human; C516850:PTPRG protein, human; C516883:PTPRS protein, human; D017027:Protein Tyrosine Phosphatases; D054623:Receptor-Like Protein Tyrosine Phosphatases, Class 2; D054630:Receptor-Like Protein Tyrosine Phosphatases, Class 4; D054633:Receptor-Like Protein Tyrosine Phosphatases, Class 5