Identification of a single sinusoidal bile salt uptake system in skate liver

Journal Article · Tue Dec 01 04:00:00 EST 1987 · American Journal of Physiology; (USA)

OSTI ID:6957869

Fricker, G; Hugentobler, G; Meier, P J; Kurz, G; Boyer, J L ^[1]

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1. Mount Desert Island Biological Laboratory, Salsbury Cove, ME (USA) Institut fur Organische Chemie und Biochemic der Universitat, Freiburg (West Germany) University Hospital, Zurich (Switzerland) Yale Univ. School of Medicine, New Haven, CT (USA)

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 revealed the presence of a predominant bile salt binding polypeptide with an apparent molecular weight of 54,000. The ({sup 3}H)-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{prime}-diisothiocyanostilbene-2,2{prime}-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 of photoaffinity labeling of hepatocytes with high concentrations of photolabile derivative reduced the V{sub max} but the K{sub m} 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{sup +}-independent transport mechanism for hepatic bile salt uptake in this primitive vertebrate.

• OSTI ID: 6957869
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 253:6; ISSN 0002-9513; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACID ANHYDRASES
ATP-ASE
BILE
BILE ACIDS
BIOCHEMICAL REACTION KINETICS
BIOCHEMISTRY
BIOLOGICAL MATERIALS
BODY
BODY FLUIDS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CHEMISTRY
CHOLIC ACID
DERIVATIZATION
DIGESTIVE SYSTEM
ELECTROPHORESIS
ENZYMES
GLANDS
HYDROGEN COMPOUNDS
HYDROLASES
HYDROXY COMPOUNDS
KINETICS
LIVER
MATERIALS
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PEPTIDES
PHOSPHOHYDROLASES
POLYPEPTIDES
PROTEINS
REACTION KINETICS
STEROIDS
STEROLS
TRITIUM COMPOUNDS
UPTAKE