title: Redox-regulated rotational coupling of receptor protein-tyrosine phosphatase alpha dimers.
abstract: Receptor protein-tyrosine phosphatase alpha (RPTP alpha) constitutively forms dimers in the membrane, and activity studies with forced dimer mutants of RPTP alpha revealed that rotational coupling of the dimer defines its activity. The hemagglutinin (HA) tag of wild type RPTP alpha and of constitutively dimeric, active RPTP alpha-F135C with a disulfide bond in the extracellular domain was not accessible for antibody, whereas the HA tag of constitutively dimeric, inactive RPTP alpha-P137C was. All three proteins were expressed on the plasma membrane to a similar extent, and the accessibility of their extracellular domains did not differ as determined by biotinylation studies. Dimerization was required for masking the HA tag, and we identified a region in the N terminus of RPTP alpha that was essential for the effect. Oxidative stress has been shown to induce a conformational change of the membrane distal PTP domain (RPTP alpha-D2). Here we report that H(2)O(2) treatment of cells induced a change in rotational coupling in RPTP alpha dimers as detected using accessibility of an HA tag in the extracellular domain as a read-out. The catalytic site Cys(723) in RPTP alpha-D2, which was required for the conformational change of RPTP alpha-D2 upon H(2)O(2) treatment, was essential for the H(2)O(2)-induced increase in accessibility. These results show for the first time that a conformational change in the intracellular domain of RPTP alpha led to a change in conformation of the extracellular domains, indicating that RPTPs have the capacity for inside-out signaling.
authors.affiliation: Hubrecht Laboratory, Netherland Institute for Developmental Biology, Uppsalalaan 8, Utrecht, 3584 CT, The Netherlands.
authors.forename: Thea
authors.initials: T
authors.lastname: van der Wijk
authors.forename: Christophe
authors.initials: C
authors.lastname: Blanchetot
authors.forename: John
authors.initials: J
authors.lastname: Overvoorde
authors.forename: Jeroen
authors.initials: J
authors.lastname: den Hertog
mesh_terms: D000818:Animals; D019921:Biotinylation; D020134:Catalytic Domain; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D019281:Dimerization; D000939:Epitopes / Q000737:chemistry; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051379:Mice; D009154:Mutation; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011233:Precipitin Tests; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry* / Q000378:metabolism; D054630:Receptor-Like Protein Tyrosine Phosphatases, Class 4; D011956:Receptors, Cell Surface; D015398:Signal Transduction; D014162:Transfection
chemical_list: D000939:Epitopes; D011956:Receptors, Cell Surface; D006861:Hydrogen Peroxide; C516841:PTPRA protein, human; D017027:Protein Tyrosine Phosphatases; C516843:Ptpra protein, mouse; D054630:Receptor-Like Protein Tyrosine Phosphatases, Class 4; D003545:Cysteine