McPhee, Jancy C. and Dang, Yan L. and Davidson, Norman and Lester, Henry A. (1998) Evidence for a Functional Interaction between Integrins and G Protein-activated Inward Rectifier K+ Channels. Journal of Biological Chemistry, 273 (52). pp. 34696-34702. ISSN 0021-9258 http://resolver.caltech.edu/CaltechAUTHORS:MCPjbc98
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Heteromultimeric G protein-activated inward rectifier K+ (GIRK) channels, abundant in heart and brain, help to determine the cellular membrane potential as well as the frequency and duration of electrical impulses. The sequence arginine-glycine-aspartate (RGD), located extracellularly between the first membrane-spanning region and the pore, is conserved among all identified GIRK subunits but is not found in the extracellular domain of any other cloned K+ channels. Many integrins, which, like channels, are integral membrane proteins, recognize this RGD sequence on other proteins, usually in the extracellular matrix. We therefore asked whether GIRK activity might be regulated by direct interaction with integrin. Here, we present evidence that mutation of the RGD site to RGE, particularly on the GIRK4 subunit, decreases or abolishes GIRK current. Furthermore, wild-type channels can be co-immunoprecipitated with integrin. The total cellular amount of expressed mutant GIRK channel protein is the same as the wild-type protein; however, the amount of mutant channel protein that localizes to the plasma membrane is decreased relative to wild-type, most likely accounting for the diminished GIRK current detected. GIRK channels appear to bind directly to integrin and to require this interaction for proper GIRK channel membrane localization and function.
|Additional Information:||Copyright © 1998 by The American Society for Biochemistry and Molecular Biology, Inc. (Received for publication, August 17, 1998, and in revised form, September 29, 1998) We thank M. Jasek for help with CHO cells; T. Ivanina for help with the Western blots and the manuscript; C. Doupnik, P. Kofuji, A. R. Horwitz, and D. Desimone for discussions; and R. Hynes and F. Lesage for antibodies. This work was supported by National Institutes of Health Grant GM-29836. The costs of publication of this article were defrayed in part by the payment of page charges. The 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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