Identification and characterization of a Kidd antigen/UT-B urea transporter expressed in human colon

Hideki Inoue, Shelley D. Jackson, Tatyana Vikulina, Janet D. Klein, Kimio Tomita, Serena M. Bagnasco

Research output: Contribution to journalArticlepeer-review


We have identified a urea transporter from the mucosa of the human colon that has characteristics consistent with a Kidd antigen/UT-B urea transporter. This intestinal urea transporter encodes a 389-amino acid peptide with a sequence identical to that previously reported for the UT-B urea transporter in erythrocytes. Expression of a UT-B 2-kb mRNA transcript and of ∼50- and ∼98-kDa UT-B proteins is detected in human colonic mucosa by Northern and Western blot analysis. The UT-B protein is localized in the cell membrane and cytoplasm of the superficial intestinal epithelium and in the epithelial cells in the crypts. A 2-kb UT-B mRNA transcript and the UT-B protein were also identified in the intestinal cell line Caco-2. The transepithelial flux of 14C urea was examined in Caco-2 cells growing on porous membrane support and was significantly inhibited by phloretin, 1,3-dimethylurea, and thiourea, suggesting that the transfer of urea across the Caco-2 monolayer could be mediated, at least in part, by the UT-B urea transporter. We conclude that the Kidd antigen/UT-B urea transporter is physiologically expressed in the human colon epithelium, where it could participate in the transport of urea across the colon mucosa.

Original languageEnglish (US)
Pages (from-to)C30-C35
JournalAmerican Journal of Physiology - Cell Physiology
Issue number1 56-1
StatePublished - Jul 2004


  • Caco-2
  • Urea transport

ASJC Scopus subject areas

  • Physiology
  • Cell Biology


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