Localization and topology of a urate transporter/channel, a galectin, in epithelium-derived cells

Joshua Z. Rappoport, Michael S. Lipkowitz, Ruth G. Abramson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Recombinant protein produced from a cDNA cloned in our laboratory (UAT) functions in lipid bilayers as a urate transporter/channel. Because UAT is a galectin, a family of proteins presumed to be soluble, the localization and topology of UAT were assessed in living cells. UAT was targeted to plasma membrane in multiple epitheliumderived cell lines and, in polarized cells, was targeted to both apical and basolateral membranes. The amino and carboxy termini of UAT were both detected on the cytoplasmic side of plasma membranes, whereas cell surface biotinylation studies demonstrated that UAT is not merely a cytosolic membrane-associated protein but contains at least one extracellular domain. Madin-Darby canine kidney cells were shown both functionally and immunologically to contain an apparent homolog of UAT; however, transfection with UAT did not modify urate uptake. Because coimmunoprecipitation studies revealed that UAT is capable of forming both homo- and heteromultimers, it is proposed that monomers of endogenous channels are in part replaced by monomers of the protein expressed subsequent to transfection, thereby maintaining constancy of urate uptake at basal levels.

Original languageEnglish (US)
Pages (from-to)C1926-C1939
JournalAmerican Journal of Physiology - Cell Physiology
Issue number6 50-6
StatePublished - 2001


  • Cell surface biotinylation
  • Confocal microscopy
  • FLAG epitope
  • Fluorescence microscopy
  • Green fluorescent protein
  • Urate uptake

ASJC Scopus subject areas

  • Physiology
  • Cell Biology


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