Sterol carrier an protein-2 (SCP-2) is intracellular lipid carrier protein that binds cholesterol, phospholipids, fatty acids and other ligands. It has been reported that expression of SCP-2 was increased in brain nerve endings or synaptosomes of chronic ethanol-treated mice and it was shown that cholesterol homeostasis was altered in brain membranes of chronic ethanol- treated animals. Ethanol may interfere with the capacity of SCP-2 to bind cholesterol as well as other lipids. This hypothesis was tested using recombinant SCP-2 and fluorescent-labeled cholesterol, phosphatidylcholine (PC), and stearic acid. The association constants (K(a)) of the ligand-SCP-2 complex were in the following order: NBD-cholesterol > NBD-PC > NBD- stearic acid. Ethanol, beginning at a concentration of 25 mM, significantly reduced the affinity of NBD-cholesterol and NBD-PC for SCP-2. Effects of ethanol on the K(a) of NBD-stearic acid was significant only at the highest concentration that was examined (200 mM). Ethanol significantly increased the B(max) of NBD-cholesterol for SCP-2 but did not have a significant effect on the B(max) of NBD-PC. Similar results were found for effects of ethanol on the K(a)s and B(max)s using pyrene-labeled cholesterol and PC. In conclusion, ethanol beginning at a physiological concentration of 25 mM inhibited binding of cholesterol and PC to SCP-2. However, effects of ethanol on lipid binding to SCP-2 were dependent on the type of lipid. Ethanol in vivo may interfere with lipid binding to SCP-2 and disrupt lipid trafficking within cells.
|Original language||English (US)|
|Number of pages||9|
|Journal||Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids|
|State||Published - Jan 29 1999|
Bibliographical noteFunding Information:
This work was supported by NIH Grants AA10806 (to N.A.A.), AG11056 (to W.G.W.), GM 31651 (to F.S.) and the Medical Research Program of the Department of Veterans Affairs (W.G.W.).
Copyright 2007 Elsevier B.V., All rights reserved.
- Lipid transport
- Sterol carrier protein-2