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The Journal of Membrane Biology

, Volume 190, Issue 3, pp 175–187 | Cite as

Polarized Expression of Shaker Channels in Epithelial Cells

  • J. Moreno
  • L.R. Cruz-Vera
  • M.R. García-Villegas
  • M. Cereijido

The polarized distribution of ion channels into an apical or a basolateral domain is a fundamental feature of the transporting-epithelial phenotype. To study the molecular motifs of the channel that may serve as addressing signal(s), as well as the cellular mechanisms that interpret it and deliver the protein accordingly, we study the fate of transfected ShIR K+ channels (a non-inactivating Shaker channel) tagged with an HA epitope, as well as several other deletants and mutants. Surface expression is triggered by Ca2+-activated cell-cell contacts, through a cascade including a phospholipase C, a protein kinase C, and the cytoskeleton of actin and tubulin, and is partially impaired by suppressing N-glycosylation with tunicamycin. Using domain-specific biotinylation we show that the channel is delivered preferentially to the basolateral domain thanks to a segment between amino acids 571 and 613, and is retained on the membrane surface due to a region involving the last three amino acids (threonine, aspartic acid, valine, TDV) of the COOH terminal. Its association with the cytoskeleton seems to take the form of a scaffold comprising actin, a-actinin, b-tubulin, mLin7 and CASK. We also observe that membrane expression of ShIR channels depends entirely on its sequence of amino acids and the conformation that the molecule may adopt, but not on its ability to translocate K+ across the membrane.

Keywords

Epithelial Cell Protein Kinase Threonine Valine Aspartic Acid 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag New York Inc. 2002

Authors and Affiliations

  • J. Moreno
    • 1
  • L.R. Cruz-Vera
    • 2
  • M.R. García-Villegas
    • 1
  • M. Cereijido
    • 1
  1. 1.Department of Physiology, Biophysics and Neurosciences, Center for Research & Advanced Studies, Av. Instituto Politécnico Nacional 2508, Col. Zacateco, México, D.F. 07300, MéxicoMX
  2. 2.Department of Genetics and Molecular Biology, Center for Research & Advanced Studies, Av. Instituto Politécnico Nacional 2508, Col. Zacateco, México, D.F. 07300, MéxicoMX

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