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Journal article

Functional reconstitution of the canalicular bile salt transport system of rat liver.

  • 1988-08-01
Published in:
  • Proceedings of the National Academy of Sciences of the United States of America. - 1988
Animals
Bile Acids and Salts
Bile Canaliculi
Bile Ducts, Intrahepatic
Biological Transport
Carrier Proteins
Glycoproteins
Male
Proteolipids
Rats
Rats, Inbred Strains
English Recent studies have suggested that the canalicular bile salt transport system of rat liver corresponds to a 100-kDa membrane glycoprotein. In the present study we attempted to functionally reconstitute the 100-kDa protein into artificial proteoliposomes. Canalicular membrane proteins were solubilized with octyl glucoside in the presence of asolectin phospholipids. The extracts were treated with preimmune serum or the 100-kDa protein selectively immunoprecipitated with a polyclonal antiserum. Proteins remaining in the supernatant were then incorporated into proteoliposomes by gel-filtration chromatography. Canalicular proteoliposomes containing the 100-kDa protein exhibited transstimulatable taurocholate uptake that could be inhibited by 4,4'-diisothiocyanato-2,2'-stilbenedisulfonic acid (DIDS). In contrast, no DIDS-sensitive transstimulatable taurocholate uptake was found in 100-kDa protein-free canalicular proteoliposomes. However, when the immunoprecipitated 100-kDa protein was dissociated from the antibodies and exclusively incorporated into liposomes, reconstitution of DIDS-sensitive transstimulatable and electrogenic taurocholate anion transport was again positive. Although incorporation of solubilized basolateral membrane proteins into liposomes also resulted in a prompt reconstitution of Na+ gradient-driven taurocholate uptake, the anti-100-kDa antibodies had no effects on the reconstituted transport activity of basolateral proteins. Thus, the findings establish that the previously characterized canalicular-specific 100-kDa protein is directly involved in the transcanalicular secretion of bile salts.
Language
  • English
Open access status
bronze
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Persistent URL
https://sonar.ch/global/documents/185502
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