Basolateral membrane expression of the Kir 2.3 channel is coordinated by PDZ interaction with Lin-7/CASK complex

Olav Olsen, H. U.I. Liu, James B. Wade, Jean Merot, And Paul A. Welling

Research output: Contribution to journalArticlepeer-review

Abstract

The basolateral membrane sorting determinant of an inwardly rectifying potassium channel, Kir 2.3, is comprised of a unique arrangement of trafficking motifs containing tandem, conceivably overlapping, biosynthetic targeting and PDZ-based signals. In the present study, we elucidate a mechanism by which a PDZ interaction coordinates one step in a basolateral membrane sorting program. In contrast to apical missorting of channels lacking the entire sorting domain, deletion of the PDZ binding motif caused channels to accumulate into an endosomal compartment. Here, we identify a new human ortholog of a Caenorhabditis elegans PDZ protein, hLin-7b, that interacts with the COOH-terminal tail of Kir 2.3 in renal epithelia. hLin-7b associates with the channel as a part of a multimeric complex on the basolateral membrane similar to a basolateral membrane complex in C. elegans vulva progenitor cells. Coexpression of hLin-7b with Kir 2.3 dramatically increases channel activity by stabilizing plasma membrane expression. The discovery identifies one component of the sorting machinery and provides evidence for a retention mechanism in a hierarchical basolateral trafficking program.

Original languageEnglish (US)
Pages (from-to)C183-C195
JournalAmerican Journal of Physiology - Cell Physiology
Volume282
Issue number1 51-1
DOIs
StatePublished - 2002
Externally publishedYes

Keywords

  • Cortical collecting duct
  • Intracellular sorting mechanism
  • Inward rectification
  • Membrane trafficking
  • Polarity
  • Potassium
  • Protein-protein interaction

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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