Wieland, Thomas and Chen, Ching-Kang and Simon, Melvin I. (1997) The Retinal Specific Protein RGS-r Competes with the γ Subunit of cGMP Phosphodiesterase for the α Subunit of Transducin and Facilitates Signal Termination. Journal of Biological Chemistry, 272 (14). pp. 8853-8856. ISSN 0021-9258 http://resolver.caltech.edu/CaltechAUTHORS:20120203-084618950
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In vertebrate photoreceptor cells, transducin mediates signaling between rhodopsin and cGMP phosphodiesterase by transiently binding its γ subunit (PDEγ). For the termination of signaling GTP hydrolysis by the transducin α subunit (TDα) GTPase is required. This reaction can be accelerated by GTPase-activating proteins (GAPs), e.g. PDEγ. Recently we identified a second retinal GAP that interacts with TDα, RGS-r. Here we compare the GAP function of RGS-r and PDEγ. Both proteins stimulated single turnover GTPase of TDα; however, RGS-r was more effective than PDEγ. When added together, PDEγ competitively inhibited the RGS-r-stimulated GTPase. In addition, the interaction of TDα in its GTP-bound form (TDα_(GTPγS)), the transition state (TDα_(GDP*AMF)) and the GDP-bound form (TDα_(GDP)) with RGS-r and PDE, respectively, was measured by surface plasmon resonance. PDEγ displayed highest affinity for TDα_(GTPγS), weaker affinity for TDα_(GDP*AMF), and weakest affinity for TDα_(GDP). RGS-r exhibited only a comparable high affinity for TDα_(GDP*AMF). We conclude that the observed competition between RGS-r and PDEγ for TDα occurs when the hydrolysis of GTP is initiated. By competing with PDEγ and removing it from TDα as well as increasing P_i release, RGS-r apparently facilitates signal termination and TDα recycling.
|Additional Information:||© 1997 by The American Society for Biochemistry and Molecular Biology, Inc. Received January 14, 1997. Revision received February 10, 1997. This work was supported by National Institute on Aging Grant AG 12288. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Recipient of a fellowship from the Deutsche Forschungsgemeinschaft.|
|Official Citation:||Thomas Wieland, Ching-Kang Chen, and Melvin I. Simon The Retinal Specific Protein RGS-r Competes with the γ Subunit of cGMP Phosphodiesterase for the α Subunit of Transducin and Facilitates Signal Termination J. Biol. Chem. 1997 272: 8853-8856. doi:10.1074/jbc.272.14.8853|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||03 Feb 2012 17:13|
|Last Modified:||03 Feb 2012 17:13|
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