Document Detail


Identification of a single sinusoidal bile salt uptake system in skate liver.
MedLine Citation:
PMID:  3425718     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
To identify the sinusoidal bile acid uptake system(s) of skate liver, photoaffinity labeling and kinetic transport studies were performed in isolated plasma membranes as well as intact hepatocytes. In both preparations photoaffinity labeling with the photolabile bile salt derivative (7,7-azo-3 alpha, 12 alpha-dihydroxy-5 beta-[3 beta-3H]cholan-24-oyl)-2-aminoethanesulfonate revealed the presence of a predominant bile salt binding polypeptide with an apparent molecular weight of 54,000. The labeling of this polypeptide was inhibited by taurocholate and cholate in a concentration-dependent manner and was virtually abolished by 1 mM of the anion transport inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. Kinetic studies of hepatic uptake with taurocholate, cholate, and the photoreactive bile salt derivative indicated the involvement of a single transport system, and all three substrates mutually competed with the uptake of each other. Finally, irreversible inhibition of the bile salt uptake system by photoaffinity labeling of hepatocytes with high concentrations (250 microM) of photolabile derivative reduced the Vmax but not the Km of taurocholate uptake. These findings strongly indicate that a single polypeptide with an apparent molecular weight of 54,000 is involved in sinusoidal bile salt uptake into skate hepatocytes. These findings contrast with similar studies in rat liver that implicate both a 54,000- and 48,000-K polypeptide in bile salt uptake and are consistent with a single Na+-independent transport mechanism for hepatic bile salt uptake in this primitive vertebrate.
Authors:
G Fricker; G Hugentobler; P J Meier; G Kurz; J L Boyer
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  253     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1987 Dec 
Date Detail:
Created Date:  1988-01-27     Completed Date:  1988-01-27     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  G816-22     Citation Subset:  IM    
Affiliation:
Mount Desert Island Biological Laboratory, Salsbury Cove, Maine 04672.
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MeSH Terms
Descriptor/Qualifier:
Affinity Labels
Animals
Anions
Bile Acids and Salts / metabolism*
Biological Transport
Cell Membrane / metabolism
Cholic Acid
Cholic Acids / metabolism
Electric Fish / physiology*
Liver / metabolism*
Membrane Proteins / metabolism
Molecular Weight
Skates (Fish) / physiology*
Taurocholic Acid / metabolism
Grant Support
ID/Acronym/Agency:
DK-25636/DK/NIDDK NIH HHS; DK-34989/DK/NIDDK NIH HHS
Chemical
Reg. No./Substance:
0/Affinity Labels; 0/Anions; 0/Bile Acids and Salts; 0/Cholic Acids; 0/Membrane Proteins; 81-24-3/Taurocholic Acid; 81-25-4/Cholic Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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