The PDZ-interacting domain of cystic fibrosis transmembrane conductance regulator is required for functional expression in the apical plasma membrane

Bryan D. Moyer, Marc Duhaime, Collin Shaw, Jerod Denton, Donna Reynolds, Katherine H. Karlson, Jason Pfeiffer, Shusheng Wang, John E. Mickle, Michal Milewski, Garry R. Cutting, William B. Guggino, Min Li, Bruce A. Stanton

Research output: Contribution to journalArticlepeer-review

146 Scopus citations

Abstract

Polarization of cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-activated chloride channel to the apical plasma membrane in epithelial cells is critical for vectorial chloride transport. Previously, we reported that the C terminus of CFTR constitutes a PDZ-interacting domain that is required for CFTR polarization to the apical plasma membrane and interaction with the PDZ domain-containing protein EBP50 (NHERF). PDZ-interacting domains are typically composed of the C-terminal three to five amino acids, which in CFTR are QDTRL. Our goal was to identify the key amino acid(s) in the PDZ-interacting domain of CFTR with regard to its apical polarization, interaction with EBP50, and ability to mediate transepithelial chloride secretion. Point substitution of the C-terminal leucine (Leu at position 0) with alanine abrogated apical polarization of CFTR, interaction between CFTR and EBP50, efficient expression of CFTR in the apical membrane, and chloride secretion. Point substitution of the threonine (Thr at position -2) with alanine or valine had no effect on the apical polarization of CFTR, but reduced interaction between CFTR and EBP50, efficient expression of CFTR in the apical membrane as well as chloride secretion. By contrast, individual point substitution of the other C-terminal amino acids (Gln at position -4, Asp at position -3 and Arg at position -1) with alanine had no effect on measured parameters. We conclude that the PDZ-interacting domain, in particular the leucine (position 0) and threonine (position -2) residues, are required for the efficient, polarized expression of CFTR in the apical plasma membrane, interaction of CFTR with EBP50, and for the ability of CFTR to mediate chloride secretion. Mutations that delete the C terminus of CFTR may cause cystic fibrosis because CFTR is not polarized, complexed with EBP50, or efficiently expressed in the apical membrane of epithelial cells.

Original languageEnglish (US)
Pages (from-to)27069-27074
Number of pages6
JournalJournal of Biological Chemistry
Volume275
Issue number35
DOIs
StatePublished - Sep 1 2000

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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