Open Access
OST alpha-OST beta: a key membrane transporter of bile acids and conjugated steroids
Nazzareno Ballatori1,Na Li1,Fang Fang1,James L Boyer1,Whitney V Christian1,Christine L Hammond1
Department of Environmental Medicine, University of Rochester School of Medicine, Rochester, NY 14642, USA.
DOI: 10.2741/3416 Volume 14 Issue 8, pp.2829-2844
Published: 01 January 2009
(This article belongs to the Special Issue Biliary transport systems, nuclear receptors and liver disease)

The organic solute and steroid transporter, Ost alpha-Ost beta, is an unusual heteromeric carrier that appears to play a central role in the transport of bile acids, conjugated steroids, and structurally-related molecules across the basolateral membrane of many epithelial cells. The transporter's substrate specificity, transport mechanism, tissue distribution, subcellular localization, transcriptional regulation, as well as the phenotype of the recently characterized Ost alpha-deficient mice all strongly support this model. In particular, the Ost alpha-deficient mice display a marked defect in intestinal bile acid and conjugated steroid absorption; a decrease in bile acid pool size and serum bile acid levels; altered intestinal, hepatic and renal disposition of known substrates of the transporter; and altered serum triglyceride, cholesterol, and glucose levels. Collectively, the data indicate that Ost alpha-Ost beta is essential for bile acid and sterol disposition, and suggest that the carrier may be involved in human conditions related to imbalances in bile acid or lipid homeostasis.

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Nazzareno Ballatori, Na Li, Fang Fang, James L Boyer, Whitney V Christian, Christine L Hammond. OST alpha-OST beta: a key membrane transporter of bile acids and conjugated steroids. Frontiers in Bioscience-Landmark. 2009. 14(8); 2829-2844.