Bile‐Salt‐Binding Polypeptides in Plasma Membranes of Hepatocytes Revealed by Photoaffinity Labelling

Kramer, Werner; Bickel, Ulrich; Buscher, Hans-Peter; Gerok, W.; Kurz, Gerhart

doi:10.1111/j.1432-1033.1982.tb07015.x

Cited by 129 publications

(33 citation statements)

References 55 publications

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“…Photoaffinity labelings of membrane subfractions from rat liver (14) and of intact hepatocytes (22) were performed at 350 nm and 30°C after 5 min of preincubation with the respective photolabile derivative; other preincubation times are indicated separately.…”

Section: Methodsmentioning

confidence: 99%

“…N8-{4-[(1-Azi-2,2,2-trifluoroethyl)benzoyl]-,B-[2,3-3H]alanyl}-6-aminophalloin with a specific radioactivity of 25 Ci/mmol (1 Ci = 37 GBq) and 7,7-azo3a,12a-dihydroxy-5l3-[3,8,12f&33H]cholan-24-oic acid § and its taurine conjugate with a specific radioactivity of 20 Ci/mmol were synthesized as described (17- Isolation of Hepatocytes and Membranes. Preparation of plasma membrane subfractions from liver, isolation of intact hepatocytes, and preparation of plasma membranes from isolated cells were carried out as described (14,21,22).…”

Section: Methodsmentioning

confidence: 99%

“…Isolation of Hepatocytes and Membranes. Preparation of plasma membrane subfractions from liver, isolation of intact hepatocytes, and preparation of plasma membranes from isolated cells were carried out as described (14,21,22).…”

Section: Methodsmentioning

confidence: 99%

“…As with phalloidin, the protecting effect of the soluble antamanide derivative was most distinct for the polypeptides with apparent Mrs of 54,000 and 48,000. Both polypeptides, the Mrs of which have been estimated previously as 2,000 and 48,000 (11)(12)(13)(14), are assumed to have a function in membrane transport of bile salts.…”

mentioning

confidence: 99%

“…Since the identification of bile-salt-binding polypeptides in sinusoidal membranes of hepatocytes has been achieved by photoaffinity labeling using different photolabile bile salt derivatives (11)(12)(13)(14) …”

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confidence: 99%

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Identity of hepatic membrane transport systems for bile salts, phalloidin, and antamanide by photoaffinity labeling.

Wieland¹,

Nassal²,

Kramer³

et al. 1984

Proc. Natl. Acad. Sci. U.S.A.

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Phalloidin, a bicyclic heptapeptide, and antamanide, a monocyclic decapeptide from the poisonous mushroom Amanita phalloides, interact with bile-salt-binding polypeptides of the hepatocyte membrane, as demonstrated by photoaffinity labeling using the photolabile bile salt derivative 7,7,-azo-3a,12a-dihydroxy-5f-cholan-24-oic acid, either unconjugated or taurine conjugated. With the photolabile derivatives of phalloidin, N8-{4-[(l-azi-2,2,2-trifluoroethyl)benzoylJ-13-alanyl}-8-aminophalloin, and of antamanide, {N6-[4-(l-azi-2,2,2-trifluoroethyl)benzoylllys6}-antamanide, the same membrane polypeptides with apparent Mrs of 54,000 and 48,000 were labeled as with the photolabile derivatives of unconjugated and conjugated bile salts. The presence of bile salts decreased markedly the extent of labeling of these phalloidinand antamanide-binding polypeptides. These results indicate that hepatic uptake systems for bile salts, phallotoxins, and the cycloamanide antamanide are identical, thus explaining the organotropism of phallotoxins.Phalloidin, a bicyclic toxic heptapeptide (1, 2) from the poisonous mushroom Amanita phalloides, is readily and selectively taken up by hepatocytes and exerts intracellularly its fatal effects on the stability of plasma membranes (3, 4). Antamanide, a monocyclic decapeptide (5) from the same toadstool, inhibits the uptake of phalloidin into hepatocytes and, in appropriate concentrations, prevents the impairment of cells (6).A series of observations suggests that the uptake of phalloidin and other phallotoxins occurs by the same transport mechanism that is physiologically responsible for the membrane transport of bile salts into hepatocytes (7-10), thus leading to an explanation for organotropism.Since the identification of bile-salt-binding polypeptides in sinusoidal membranes of hepatocytes has been achieved by photoaffinity labeling using different photolabile bile salt derivatives (11-14), differential labeling in the presence of phalloidin or antamanide should give indirect proof for the involvment of the same polypeptides in hepatic membrane transport. Direct proof is established if photoaffinity labeling of plasma membranes and of isolated hepatocytes, using photolabile derivatives of phalloidin and antamanide, results in the labeling of identical polypeptides. This labeling must be decreased in the presence of bile salts. Photoaffinity labeling studies with 7,7-azo-3a,12a-dihydroxy-53-cholan-24-oic acid and its taurine conjugate, with N8-{4-[(1-azi-2,2,2-trifluoroethyl)benzoyl]-p-alanyl}-8-aminophalloin and with {Ne-[4-(1-azi-2 ,2 ,2-trifluoroethyl)benzoyl]lys6}-antamanide demonstrated that identical polypeptides are involved in the uptake of bile salts, phalloidin, and antamanide into hepatocytes. MATERIALS AND METHODSMaterials. Phalloidin was a sample from the laboratory of Theodor Wieland. The water-soluble O-carboxymethyl-tyr6-antamanide was prepared as described (15, 16) and its sodium salt was used. N8-{4-[(1-Azi-2,2,2-trifluoroethyl)benzoyl]-,B-[2,3-3H]alanyl}-6-aminoph...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Identity of hepatic membrane transport systems for bile salts, phalloidin, and antamanide by photoaffinity labeling.

Wieland¹,

Nassal²,

Kramer³

et al. 1984

Proc. Natl. Acad. Sci. U.S.A.

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Organic Anion Uptake by Hepatocytes

Wolkoff

2014

Comprehensive Physiology

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Many of the compounds taken up by the liver are organic anions that circulate tightly bound to protein carriers such as albumin. The fenestrated sinusoidal endothelium of the liver permits these compounds to have access to hepatocytes. Studies to characterize hepatic uptake of organic anions through kinetic analyses, suggested that it was carrier-mediated. Attempts to identify specific transporters by biochemical approaches were largely unsuccessful and were replaced by studies that utilized expression cloning. These studies led to identification of the organic anion transport proteins (oatps), a family of 12 transmembrane domain glycoproteins that have broad and often overlapping substrate specificities. The oatps mediate Na+-independent organic anion uptake. Other studies identified a seven transmembrane domain glycoprotein, Na+/taurocholate transporting protein (ntcp) as mediating Na+-dependent uptake of bile acids as well as other organic anions. Although mutations or deficiencies of specific members of the oatp family have been associated with transport abnormalities, there have been no such reports for ntcp, and its physiologic role remains to be determined, although expression of ntcp in vitro recapitulates the characteristics of Na+-dependent bile acid transport that is seen in vivo. Both ntcp and oatps traffic between the cell surface and intracellular vesicular pools. These vesicles move through the cell on microtubules, using the microtubule based motors dynein and kinesins. Factors that regulate this motility are under study and may provide a unique mechanism that can alter the plasma membrane content of these transporters and consequently their accessibility to circulating ligands.

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