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.).
- Lipid transport
- Sterol carrier protein-2