Liu, Mingyao and Yu, Bo and Nakanishi, Osamu and Wieland, Thomas and Simon, Melvin (1997) The Ca2+-dependent Binding of Calmodulin to an N-terminal Motif of the Heterotrimeric G Protein beta Subunit. Journal of Biological Chemistry, 272 (30). pp. 18801-18807. ISSN 0021-9258 http://resolver.caltech.edu/CaltechAUTHORS:LIUjbc97
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Ca2+ ion concentration changes are critical events in signal transduction. The Ca2+-dependent interactions of calmodulin (CaM) with its target proteins play an essential role in a variety of cellular functions. In this study, we investigated the interactions of G protein beta gamma subunits with CaM. We found that CaM binds to known beta gamma subunits and these interactions are Ca2+-dependent. The CaM-binding domain in Gbeta gamma subunits is identified as Gbeta residues 40-63. Peptides derived from the Gbeta protein not only produce a Ca2+-dependent gel mobility shifting of CaM but also inhibit the CaM-mediated activation of CaM kinase II. Specific amino acid residues critical for the binding of Gbeta gamma to CaM were also identified. We then investigated the potential function of these interactions and showed that binding of CaM to Gbeta gamma inhibits the pertussis toxin-catalyzed ADP-ribosylation of Galpha o subunits, presumably by inhibiting heterotrimer formation. Furthermore, we demonstrated that interaction with CaM has little effect on the activation of phospholipase C-beta 2 by Gbeta gamma subunits, supporting the notion that different domains of Gbeta gamma are responsible for the interactions of different effectors. These findings shed light on the molecular basis for the interactions of Gbeta gamma with Ca2+-CaM and point to the potential physiological significance of these interactions in cellular functions.
|Additional Information:||©1997 by The American Society for Biochemistry and Molecular Biology, Inc. (Received for publication, January 29, 1997, and in revised form, April 29, 1997) We thanks Dr. Silvia Cavagnero (Division of Chemistry, Caltech) for her help and discussion with the fluorescence measurements of the peptide-protein interactions and Dr. A.R. Means (Duke University) for cDNA clones of calmodulin. This work was supported by a grant from the National Institutes of Health. 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.|
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|Deposited On:||08 Nov 2006|
|Last Modified:||26 Dec 2012 09:16|
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