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

J. Biol. Chem., Vol. 279, Issue 16, 16295-16300, April 16, 2004

This Article Full Text Full Text (PDF) All Versions of this Article: 279/16/16295    most recent M312838200v1 Alert me when this article is cited 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 Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sun, A.-Q. Articles by Suchy, F. J. Search for Related Content PubMed PubMed Citation Articles by Sun, A.-Q. Articles by Suchy, F. J. Social Bookmarking                      What's this?

Association of the 16-kDa Subunit c of Vacuolar Proton Pump with the Ileal Na⁺-dependent Bile Acid Transporter

PROTEIN-PROTEIN INTERACTION AND INTRACELLULAR TRAFFICKING^*

An-Qiang Sun, Natarajan Balasubramaniyan, Chuan-Ju Liu¶, Mohammad Shahid, and Frederick J. Suchy

From the Department of Pediatrics, Mount Sinai School of Medicine, New York, New York 10029 and the ^¶Department of Orthopaedic Surgery, New York University, New York, New York 10003

The rat ileal apical sodium-dependent bile acid transporter (Asbt) transports conjugated bile acids in a Na⁺-dependent fashion and localizes specifically to the apical surface of ileal enterocytes. The mechanisms that target organic anion transporters to different domains of the ileal enterocyte plasma membrane have not been well defined. Previous studies (Sung, A.-Q., Arresa, M. A., Zeng, L., Swaby, I'K., Zhou, M. M., and Suchy, F. J. (2001) J. Biol. Chem. 276, 6825–6833) from our laboratory demonstrated that rat Asbt follows an apical sorting pathway that is brefeldin A-sensitive and insensitive to protein glycosylation, monensin treatment, and low temperature shift. Furthermore, a 14-mer signal sequence that adopts a -turn conformation is required for apical localization of rat Asbt. In this study, a vacuolar proton pump subunit (VPP-c, the 16-kDa subunit c of vacuolar H⁺-ATPase) has been identified as an interacting partner of Asbt by a bacterial two-hybrid screen. A direct protein-protein interaction between Asbt and VPP-c was confirmed in an in vitro pull-down assay and in an in vivo mammalian two-hybrid analysis. Indirect immunofluorescence confocal microscopy demonstrated that the Asbt and VPP-c colocalized in transfected COS-7 and MDCK cells. Moreover, bafilomycin A1 (a specific inhibitor of VPP) interrupted the colocalization of Asbt and VPP-c. A taurocholate influx assay and membrane biotinylation analysis showed that treatment with bafilomycin A1 resulted in a significant decrease in bile acid transport activity and the apical membrane localization of Asbt in transfected cells. Thus, these results suggest that the apical membrane localization of Asbt is mediated in part by the vacuolar proton pump associated apical sorting machinery.

Received for publication, November 24, 2003 , and in revised form, January 14, 2004.

^* This work was supported in part by the National Institutes of Health Grant HD20632 (to F. J. S.). Confocal laser scanning microscopy was performed at the Mount Sinai School of Medicine-Confocal Laser Scanning Microscopy core facility, supported with funding from the National Institutes of Health Shared Instrumentation Grant 1 S10 RR0 9145-01 and National Science Foundation Major Research Instrumentation Grant DBI-9724504. 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.

To whom correspondence should be addressed: Dept. of Pediatrics, Box 1664, Mount Sinai Medical School, One Gustave L. Levy Place, New York, NY 10029-6574. Tel.: 212-241-2366; Fax: 212-426-1972; E-mail: An-Qiang.Sun{at}mssm.edu.

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

This article has been cited by other articles:

				F. Annaba, Z. Sarwar, P. Kumar, S. Saksena, J. R. Turner, P. K. Dudeja, R. K. Gill, and W. A. Alrefai Modulation of ileal bile acid transporter (ASBT) activity by depletion of plasma membrane cholesterol: association with lipid rafts Am J Physiol Gastrointest Liver Physiol, February 1, 2008; 294(2): G489 - G497. [Abstract] [Full Text] [PDF]

				A.-Q. Sun, N. Balasubramaniyan, K. Xu, C. J. Liu, V. M. Ponamgi, H. Liu, and F. J. Suchy Protein-protein interactions and membrane localization of the human organic solute transporter Am J Physiol Gastrointest Liver Physiol, June 1, 2007; 292(6): G1586 - G1593. [Abstract] [Full Text] [PDF]

				A.-Q. Sun, N. Balasubramaniyan, H. Chen, M. Shahid, and F. J. Suchy Identification of Functionally Relevant Residues of the Rat Ileal Apical Sodium-dependent Bile Acid Cotransporter J. Biol. Chem., June 16, 2006; 281(24): 16410 - 16418. [Abstract] [Full Text] [PDF]