An Apical PDZ Protein Anchors the Cystic Fibrosis Transmembrane Conductance Regulator to the Cytoskeleton*
- Douglas B. Short‡,
- Kevin W. Trotter‡,
- David Reczek§,
- Silvia M. Kreda¶,
- Anthony Bretscher§,
- Richard C. Boucher¶,
- M. Jackson Stutts¶ and
- Sharon L. Milgram‡‖
- From the ‡Department of Physiology and ¶The Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, North Carolina 27599 and the§Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853
Abstract
The function of the cystic fibrosis transmembrane conductance regulator (CFTR) as a Cl− channel in the apical membrane of epithelial cells is extensively documented. However, less is known about the molecular determinants of CFTR residence in the apical membrane, basal regulation of its Cl− channel activity, and its reported effects on the function of other transporters. These aspects of CFTR function likely require specific interactions between CFTR and unknown proteins in the apical compartment of epithelial cells. Here we report that CFTR interacts with the recently discovered protein, EBP50 (ERM-binding phosphoprotein 50). EBP50 is concentrated at the apical membrane in human airway epithelial cells, in vivo, and CFTR and EBP50 associate inin vitro binding assays. The CFTR-EBP50 interaction requires the COOH-terminal DTRL sequence of CFTR and utilizes either PDZ1 or PDZ2 of EBP50, although binding to PDZ1 is of greater affinity. Through formation of a complex, the interaction between CFTR and EBP50 may influence the stability and/or regulation of CFTR Cl−channel function in the cell membrane and provides a potential mechanism through which CFTR can affect the activity of other apical membrane proteins.
Footnotes
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↵* This work was supported by Grant MILGRA9710 from the Cystic Fibrosis Foundation, National Institutes of Health Grants R29DK50744, GM36652, P50 HL42384, and P01 HL34322, and by a grant from the Center for Gastrointestinal Biology and Disease at the University of North Carolina at Chapel Hill.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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↵‖ To whom correspondence should be addressed: Dept. of Physiology, The University of North Carolina, CB 7545, Chapel Hill, NC 27599-7545. Tel.: 919-966-9792; Fax: 919-966-6927; E-mail:milg{at}med.unc.edu.
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↵1 The abbreviations used are: CF, cystic fibrosis; CFTR, cystic fibrosis transmembrane conductance regulator; EBP50, ERM-binding phosphoprotein 50; NHE-RF, Na+/H+exchange regulatory factor; PAGE, polyacrylamide gel electrophoresis; GST, glutathione S-transferase; PCR, polymerase chain reaction.
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- Received April 24, 1998.
- Revision received June 4, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
