HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 283, Issue 36, 24718-24728, September 5, 2008

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 283/36/24718    most recent M803497200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by An, N. Articles by Lanier, S. M. Search for Related Content PubMed PubMed Citation Articles by An, N. Articles by Lanier, S. M. Social Bookmarking                      What's this?

The PDZ and Band 4.1 Containing Protein Frmpd1 Regulates the Subcellular Location of Activator of G-protein Signaling 3 and Its Interaction with G-proteins^*

Ningfei An, Joe B. Blumer, Michael L. Bernard, and Stephen M. Lanier¹¹

From the Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112 and the Department of Pharmacology, Medical University of South Carolina, Charleston, South Carolina 29425

Activator of G-protein signaling 3 (AGS3) is one of nine mammalian proteins containing one or more G-protein regulatory (GPR) motifs that stabilize the GDP-bound conformation of G_i. Such proteins have revealed unexpected functional diversity for the "G-switch" in the control of events within the cell independent of the role of heterotrimeric G-proteins as transducers for G-protein-coupled receptors at the cell surface. A key question regarding this class of proteins is what controls their subcellular positioning and interaction with G-proteins. We conducted a series of yeast two-hybrid screens to identify proteins interacting with the tetratricopeptide repeat (TPR) of AGS3, which plays an important role in subcellular positioning of the protein. We report the identification of Frmpd1 (FERM and PDZ domain containing 1) as a regulatory binding partner of AGS3. Frmpd1 binds to the TPR domain of AGS3 and coimmunoprecipitates with AGS3 from cell lysates. Cell fractionation indicated that Frmpd1 stabilizes AGS3 in a membrane fraction. Upon cotransfection of COS7 cells with Frmpd1-GFP and AGS3-mRFP, AGS3-mRFP is observed in regions of the cell cortex and also in membrane extensions or processes where it appears to be colocalized with Frmpd1-GFP based upon the merged fluorescent signals. Frmpd1 knockdown (siRNA) in Cath.a-differentiated neuronal cells decreased the level of endogenous AGS3 in membrane fractions by 50% and enhanced the ₂-adrenergic receptor-mediated inhibition of forskolin-induced increases in cAMP. The coimmunoprecipitation of Frmpd1 with AGS3 is lost as the amount of G_i3 in the cell is increased and AGS3 apparently switches its binding partner from Frmpd1 to G_i3 indicating that the interaction of AGS3 with Frmpd1 and G_i3 is mutually exclusive. Mechanistically, Frmpd1 may position AGS3 in a membrane environment where it then interacts with G_i in a regulated manner.

Received for publication, May 8, 2008 , and in revised form, June 9, 2008.

^* This work was supported, in whole or in part, by National Institutes of Health Grants MH90531 (to S. M. L.), NS24821 (to S. M. L.), and F32MH65092 (to J. B. B.). 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.

The on-line version of this article (available at http://www.jbc.org) contains supplemental Figs. S1–S5.

¹ Supported by a Research Scholar Award from Yamanouchi Pharmaceutical Company (now Astellas Pharma) and the Lederle Laboratories/David R. Bethune Professorship in Pharmacology at Louisiana State University Health Sciences Center, New Orleans

¹ To whom correspondence should be addressed: Dept. of Pharmacology, Medical University of South Carolina, Charleston, SC 29425. Tel.: 843-792-7134; E-mail: lanier{at}musc.edu.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?