|
|
||||||||
AJP - Gastrointestinal and Liver Physiology, Vol 258, Issue 5 728-G737, Copyright © 1990 by American Physiological Society
ARTICLES |
C. J. Sippel, M. Ananthanarayanan and F. J. Suchy
Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06510.
The aim of this study was to isolate the Na(+)-independent bile acid transporter from rat canalicular plasma membranes by affinity chromatography. The affinity matrix used consisted of lysylcholic acid covalently linked to CH-Sepharose 4B, resulting in an anionic ligand essentially identical to glycocholic acid. The protein fraction, adsorbed and eluted from the affinity column, was markedly enriched in a 100-kDa band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) compared with the total membrane and membrane extract. The 100-kDa band, further purified by preparative SDS-PAGE, was electroeluted from excised gel fragments and used as an immunogen for antibody production in rabbits. The immune serum, but not preimmune serum, specifically recognized a single, 100-kDa polypeptide on one- and two-dimensional immunoblots of canalicular membranes. In contrast, no reactivity was observed with proteins in liver basolateral or ileal brush-border membranes. The 125I-labeled protein was immunoprecipitated from membrane extracts solubilized in NP-40 and was found to migrate with a pI of 5.3 on two-dimensional electrophoresis. The apparent molecular weight of the protein was reduced by 50% after deglycosylation with N-glycanase. The 100-kDa protein was localized specifically and exclusively by immunocytochemical methods to the bile canalicular domain of the hepatocyte plasma membrane. Moreover, the immunoglobin G fraction prepared from the antiserum significantly inhibited taurocholate transport by canalicular membrane vesicles and decreased the covalent labeling of the 100-kDa protein by the anion transport inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. Thus the isolation of a single 100-kDa protein by bile acid-affinity chromatography, as well as the inhibitory effects of antibodies directed against this polypeptide, provide further support for its role in the canalicular transport of bile acids.
This article has been cited by other articles:
![]() |
W. Geng, A. J. Schwab, T. Horie, C. A. Goresky, and K. S. Pang Hepatic Uptake of Bromosulfophthalein-Glutathione in Perfused Eisai Hyperbilirubinemic Mutant Rat Liver: A Multiple-Indicator Dilution Study J. Pharmacol. Exp. Ther., February 1, 1998; 284(2): 480 - 492. [Abstract] [Full Text] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |