Demonstration of bile acid transport across the mammalian peroxisomal membrane.
It is well established that peroxisomes play a crucial role in de novo bile acid biosynthesis. The primary bile acids resulting from peroxisomal beta-oxidation are conjugated to either glycine or taurine in the peroxisomal lumen by a bile acid aminotransferase (BAT). These conjugated bile acids are subsequently secreted into the bile. In this paper we show that the export of glycine- and taurine-conjugated bile acids from mammalian peroxisomes proceeds via specific transporter. The transport activity of this protein was detected by reconstitution of peroxisomal membrane proteins in liposomes and measuring the uptake of radiolabeled substrates into these proteoliposomes. The transporter was further characterized using this assay, which led to the identification of DIDS as an inhibitor of the peroxisomal bile-acid transporter, and allowed us to establish some kinetic parameters for the transport activity.
Visser
Wouter F
WF
University of Amsterdam, Academic Medical Centre, Department of Clinical Chemistry and Pediatrics, Laboratory Genetic Metabolic Diseases, F0-224, Meibergdreef 9, Amsterdam, 1105 AZ, The Netherlands. w.f.visser@amc.uva.nl
van Roermund
Carlo W T
CW
Ijlst
Lodewijk
L
Waterham
Hans R
HR
Wanders
Ronald J A
RJ
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001647:Bile Acids and Salts / Q000378:metabolism*; D001693:Biological Transport, Active / Q000502:physiology; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D008081:Liposomes / Q000378:metabolism*; D020675:Peroxisomes / Q000378:metabolism*
D001647:Bile Acids and Salts; D008081:Liposomes; D000255:Adenosine Triphosphate