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

作者：Ari J. Bergwerk, Xiaoying Shi, Alexander Charles Ford, Naoaki KANAI, Emmanuel Jacquemin, Robert David Burk, Shuyan Bai, Phyllis M. Novikoff, Bruno Stieger, Peter J. Meier, V. L. Schuster, Allan W. Wolkoff · 发表于：American Journal of Physiology-Gastrointestinal and Liver Physiology · 年份：1996 · DOI：10.1152/ajpgi.1996.271.2.g231 · 被引用次数：181 · 研究领域：Drug Transport and Resistance Mechanisms、Ion Transport and Channel Regulation、Amino Acid Enzymes and Metabolism

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 Na2CO3-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 apical plasma membrane localization in the S3 segmen...