High impact information on OSTalpha

• Transport in OSTalpha-OSTbeta-expressing Xenopus laevis oocytes was unaffected by depletion of intracellular adenosine triphosphate, or by changes in transmembrane Na(+), K(+), H(+), or Cl(-) concentration gradients [1].
• Indirect immunofluorescence microscopy localized OSTalpha and OSTbeta to the basolateral membrane of mouse, rat, and human ileal enterocytes, renal proximal tubular cells, and cholangiocytes [1].
• OSTalpha-OSTbeta: a major basolateral bile acid and steroid transporter in human intestinal, renal, and biliary epithelia [1].
• Human and mouse OSTalpha-OSTbeta also were able to mediate transport of taurocholate, digoxin, and prostaglandin E2 but not of estradiol 17beta-d-glucuronide or p-aminohippurate [2].
• OSTalpha and OSTbeta were able to reach the oocyte plasma membrane when expressed either individually or in pairs, indicating that co-expression is not required for proper membrane targeting [2].

Anatomical context of OSTalpha

• At the basolateral domain of ileal enterocytes, bile acids are extruded into portal blood by the heterodimeric organic solute transporter OSTalpha/OSTbeta [3].
• Interestingly, OSTalpha and OSTbeta mRNAs were highly expressed and widely distributed in human tissues, with the highest levels occurring in the testis, colon, liver, small intestine, kidney, ovary, and adrenal gland [2].
• Glutathione transferases (GSTs) catalyze the committed step in the MAP; GST-mu and GST-pi, but not OST-alpha, were detected in neurons and astrocytes in cerebrum from AD patients and controls [4].

Associations of OSTalpha with chemical compounds

• HepG2 cells treated for 24 h with chenodeoxycholic acid, a selective FXR ligand, had higher levels of OSTalpha and OSTbeta mRNA and protein [5].
• When OSTalpha and OSTbeta are coexpressed in Xenopus oocytes, they are able to mediate transport of estrone 3-sulfate, dehydroepiandrosterone 3- sulfate, taurocholate, digoxin, and prostaglandin E2, indicating a role in the disposition of key cellular metabolites or signaling molecules [6].

Physical interactions of OSTalpha

• Two functional FXR binding motifs were identified in the OSTalpha gene and one in the OSTbeta gene [3].

Other interactions of OSTalpha

• Although the transport function of OSTalpha/OSTbeta has been characterized, little is known about the regulation of its expression [3].
• The nuclear receptor for bile acids, FXR, transactivates human organic solute transporter-alpha and -beta genes [3].

References