Immunologic distribution of an organic anion transport protein in rat liver and kidney

Ari J. Bergwerk, Xiaoying Shi, Allison C. Ford, Naoaki Kanai, Emmanuel Jacquemin, Robert D. Burk, Shuang Bai, Phyllis M. Novikoff, Bruno Stieger, Peter J. Meier, Victor L. Schuster, Allan W. Wolkoff

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185 Scopus citations


A Na+-independent organic anion transport protein was recently cloned from rat liver using a Xenopus laevis oocyte expression system [E. Jacquemin, B. Hagenbuch, B. Stieger, A. W. Wolkoff, and P. J. Meier, Proc. Natl. Acad. Sci. USA 91: 133-137, 1994]. Although expression of this protein is sufficient for cells to transport the organic anion bromosulfophthalein, little is known about its cell biology or biochemical characteristics. Northern blot analysis performed under high-stringency conditions revealed hybridization with RNA only from liver and kidney; transcripts appeared the same in these two organs. Within kidney, hybridization was greatest when RNA extracted from the outer medulla was used. Immunoblot analysis revealed that in liver, the transporter was enriched in 0.1 M Na2C3-extracted membranes and sinusoidal plasma membrane preparations, consistent with its being an integral membrane protein. This 80-kDa protein migrated as a 65-kDa protein after treatment with N-glycanase. Immunomorphological examination of liver revealed basolateral plasma membrane localization. In 0.1 M Na2CO3- extracted membranes of kidney, the transporter migrated as an 83-kDa protein on nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). On reduction, it resolved into peptides of 33 and 37 kDa. SDS- PAGE migration of the liver protein was unaffected by reduction. Immunomorphological examination of kidney revealed epical plasma membrane localization in the S3 segment of the proximal tubule of the outer medulla. Differential processing and trafficking of this transporter in liver and kidney may have important functional and regulatory consequences.

Original languageEnglish (US)
Pages (from-to)G231-G238
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Issue number2 34-2
StatePublished - Aug 1996


  • protein processing
  • protein trafficking
  • sulfobromophthalein

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)


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