Photoaffinity labeling studies of the rat renal sodium bile salt cotransport system.
The uptake of a photolabile taurocholate derivative, (7,7-azo-3 alpha, 12 alpha-dihydroxy-5 beta-cholan-24-oyl)-2-aminoethanesulfonate, 7,7-azo-TC, into rat renal brush-border membrane vesicles was stimulated by Na+ and inhibited by taurocholate indicating an interaction with the Na+/bile salt cotransport system. Irradiation of membrane vesicles in the presence of 7,7-azo-TC inhibited Na+-dependent taurocholate uptake irreversibly. Photoaffinity labeling with [3H]7,7-azo-TC resulted in a predominant incorporation of radioactivity into a polypeptide with apparent molecular weight of 99,000. These results suggest that the proteins involved in Na+/bile salt cotransport are similar in renal and ileal brush-border membranes, but differ from those in hepatocytes.
D000345:Affinity Labels; D000818:Animals; D001391:Azo Compounds; D001647:Bile Acids and Salts / Q000378:metabolism*; D001693:Biological Transport, Active; D066298:In Vitro Techniques; D007668:Kidney / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008871:Microvilli / Q000378:metabolism; D010782:Photolysis; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism*
D000345:Affinity Labels; D001391:Azo Compounds; D001647:Bile Acids and Salts; D008565:Membrane Proteins; C037641:(7,7-azo-3,12-dihydroxy-5-cholan-24-oyl)-2-aminoethanesulfonic acid; D012964:Sodium