Cholesterol Interaction with the Daunorubicin Binding Site of P-Glycoprotein
Authors: Wang E-j.; Casciano C.N.; Clement R.P.; Johnson W.W.
Source: Biochemical and Biophysical Research Communications, Volume 276, Number 3, October 2000 , pp. 909-916(8)
Publisher: Academic Press
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Abstract:
The inherent complexities of cholesterol disposition and metabolism preclude a single transmembrane active transport avenue for this steroid-precursor, cell-membrane constituent. Yet the ABC (ATP binding cassette) transporters are inextricably linked to elements of cholesterol disposition. Recent observations have suggested that, under certain settings, the ABC transporter P-glycoprotein (P-gp) performs a direct role in cholesterol disposition. The gene product of MDR1 (multidrug resistance transporter), P-glycoprotein also confers protection against xenobiotics. Using a whole cell assay in which the retention of a marker substrate is evaluated and quantified, we studied the ability of cholesterol to inhibit directly the function of this transporter. In a NIH-G185 cell line presenting an overexpressed amount of the human transporter P-gp, cholesterol caused dramatic inhibition of daunorubicin transport with an IC50 of about 8 
M yet had no effect on the parent cell line nor rhodamine 123 transport. Additionally, using the ATP-hydrolysis assay, we showed that cholesterol increases P-gp-mediated ATP hydrolysis by approximately 1.6-fold with a Ks of 5 M. Suggesting that cholesterol directly interacts with the substrate binding site of P-gp, these results are consistent with cholesterol being transported by MDR1 P-gp. Copyright 2000 Academic Press.
Keywords: cholesterol; P-glycoprotein; MDR; transport
Language: English
Document Type: Research article
Affiliations: Drug Metabolism and Pharmacokinetics, Schering-Plough Research Institute, Lafayette, New Jersey, 07848:
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