title: Roles of superoxide radical anion in signal transduction mediated by reversible regulation of protein-tyrosine phosphatase 1B.
abstract: Growth factors induce intracellular production of reactive oxygen species in non-phagocytic cells and elevation of their phosphorylated protein tyrosine level. The latter can be achieved by activating protein-tyrosine kinases and/or inactivating protein-tyrosine phosphatases (PTPs). A highly abundant PTP, PTP-1B, is known to be inactivated by oxidation of its catalytic site Cys-215. We show that O-(2) is kinetically more efficient and chemically more specific oxidant than H(2)O(2) for inactivating PTP-1B. The second-order rate constant for the O-(2)- and H(2)O(2)-mediated inactivation is 334 +/- 45 M(-1) s(-1) and 42.8 +/- 3.8 M(-1) s(-1), respectively. PTP-1B oxidized by H(2)O(2) exhibits significantly more oxidized methionine residues and shows a lower degree of reversibility. The initial oxidative product, the Cys-215 sulfenic derivative, can easily be oxidized further to its irreversible sulfinic and sulfonic derivatives. This step is prevented by glutathionylation of the sulfenic derivative to form a S-glutathionylated PTP-1B, which can be reactivated by dithiothreitol or thioltransferase. Thus, a signal transduction mechanism mediated by the O-(2) and the participation of glutathione is proposed for the regulation of PTP-1B. This mechanism is supported by the in vivo demonstration that glutathionylated PTP-1B at Cys-215 is formed in A431 cells when they were treated with epidermal growth factor.
authors.affiliation: Laboratory of Biochemistry, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: W C
authors.initials: WC
authors.lastname: Barrett
authors.forename: J P
authors.initials: JP
authors.lastname: DeGnore
authors.forename: Y F
authors.initials: YF
authors.lastname: Keng
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Zhang
authors.forename: M B
authors.initials: MB
authors.lastname: Yim
authors.forename: P B
authors.initials: PB
authors.lastname: Chock
mesh_terms: D000838:Anions / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D002374:Catalase / Q000494:pharmacology; D002853:Chromatography, Liquid; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007700:Kinetics; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000378:metabolism*; D010084:Oxidation-Reduction; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction; D013481:Superoxides / Q000378:metabolism*; D013997:Time Factors; D014407:Tumor Cells, Cultured; D019820:Xanthine / Q000494:pharmacology
chemical_list: D000838:Anions; D002352:Carrier Proteins; D008565:Membrane Proteins; D017382:Reactive Oxygen Species; D013481:Superoxides; D019820:Xanthine; D006861:Hydrogen Peroxide; D002374:Catalase; C516607:PTPN1 protein, human; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases