title: OST alpha-OST beta: a key membrane transporter of bile acids and conjugated steroids.
abstract: 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.
authors.affiliation: Department of Environmental Medicine, University of Rochester School of Medicine, Rochester, NY 14642, USA. Ned_Ballatori@urmc.rochester.edu
authors.forename: Nazzareno
authors.initials: N
authors.lastname: Ballatori
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.forename: Fang
authors.initials: F
authors.lastname: Fang
authors.forename: James L
authors.initials: JL
authors.lastname: Boyer
authors.forename: Whitney V
authors.initials: WV
authors.lastname: Christian
authors.forename: Christine L
authors.initials: CL
authors.lastname: Hammond
mesh_terms: D001647:Bile Acids and Salts / Q000096:biosynthesis / Q000378:metabolism*; D001692:Biological Transport; D019281:Dimerization; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D013256:Steroids / Q000378:metabolism*
chemical_list: D001647:Bile Acids and Salts; D026901:Membrane Transport Proteins; D013256:Steroids