ROS Activation of G{alpha}

doi:10.1126/stke.2002.124.tw108

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Sci. STKE, 19 March 2002
Vol. 2002, Issue 124, p. tw108
[DOI: 10.1126/stke.2002.124.tw108]

EDITORS' CHOICE

REACTIVE OXYGEN SPECIES ROS Activation of G ${alpha}$

Although treatment of myocytes with the reactive oxygen species (ROS) H₂O₂ activates the heterotrimeric GTP-binding proteins G_i and G_o in a receptor-independent manner, the mechanismic detail of this effect has not been clear. Nishida et al. report that H₂O₂ is converted to a more reactive hydroxyl radical in the presence of Fe²⁺. Myocytes treated with a cell-permeable Fe²⁺ chelator inhibited the effect of H₂O₂ and subsequent activation of mitogen-activated protein kinase. This highly reactive ROS modified two specific cyteine resideus present only in G ${alpha}$ _i and G ${alpha}$ _o in vitro. The modification caused dissociation of G ${alpha}$ _i from the Gß subunit and increased GTP binding. Mutation of the cysteines in G ${alpha}$ _i inhibited subunit dissociation and the activating effect of the ROS radical. Treatment of G ${alpha}$ _i with UV light in vitro, which generates ROS from O₂ dissolved in solution, also required the presence of the critical cysteines, suggesting that such cellular stress can activate G proteins through ROS generation.

M. Nishida, K. L. Schey, S. Takagahara, K. Kontani, T. Katada, Y. Urano, T. Nagano, T. Nagao, H. Kurose, Activation mechanism of G_i and G_o by reactive oxygen species. J. Biol. Chem. 277, 9036-9042 (2002). [Abstract] [Full Text]

Citation: ROS Activation of G ${alpha}$ . Sci. STKE 2002, tw108 (2002).