Functional Expression Cloning and Characterization of the Hepatocyte Na+/Bile Acid Cotransport System

Liver parenchymal cells continuously extract high amounts of bile acids from portal blood plasma. This uptake process is mediated by a Nasd+/bile acid cotransport system. A cDNA encoding the rat liver bile acid uptake system has been isolated by expression cloning in Xenopus laevis oocytes. The clon...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1991-12, Vol.88 (23), p.10629-10633
Main Authors: Hagenbuch, Bruno, Stieger, Bruno, Foguet, Montserrat, Lubbert, Hermann, Meier, Peter J.
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Amino acids
Analytical, structural and metabolic biochemistry
Animals
Base Sequence
Bile acids
Binding and carrier proteins
Biological and medical sciences
Blotting, Northern
Carrier Proteins - genetics
Carrier Proteins - isolation & purification
Carrier Proteins - metabolism
Cloning, Molecular
Complementary DNA
DNA - genetics
DNA - isolation & purification
Female
Fundamental and applied biological sciences. Psychology
Gene Library
Hepatocytes
Liver
Liver - metabolism
Messenger RNA
Molecular Sequence Data
Molecular Weight
Nucleotides
Oocytes
Oocytes - metabolism
Organic Anion Transporters, Sodium-Dependent
Protein Conformation
Proteins
Rats
Restriction Mapping
RNA
RNA, Messenger - genetics
Sodium - metabolism
Symporters
Taurocholic Acid - metabolism
Xenopus laevis
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Summary:Liver parenchymal cells continuously extract high amounts of bile acids from portal blood plasma. This uptake process is mediated by a Nasd+/bile acid cotransport system. A cDNA encoding the rat liver bile acid uptake system has been isolated by expression cloning in Xenopus laevis oocytes. The cloned transporter is strictly sodium-dependent and can be inhibited by various non-bile-acid organic compounds. Sequence analysis of the cDNA revealed an open reading frame of 1086 nucleotides coding for a protein of 362 amino acids (calculated molecular mass 39 kDa) with five possible N-linked glycosylation sites and seven putative transmembrane domains. Translation experiments in vitro and in oocytes indicate that the transporter is indeed glycosylated and that its polypeptide backbone has an apparent molecular mass of 33-35 kDa. Northern blot analysis with the cloned probe revealed crossreactivity with mRNA species from rat kidney and intestine as well as from liver tissues of mouse, guinea pig, rabbit, and man.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.88.23.10629