ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Glycosphingolipids and cholesterol form lateral assemblies, or lipid ‘rafts’, within biological membranes. Lipid rafts are routinely studied biochemically as low-density, detergent-insoluble complexes (in non-ionic detergents at 4°C; DIGs, detergent-insoluble glycosphingolipid/cholesterol microdomains). Recent discrepancies recommended a re-evaluation of the conditions used for the biochemical analysis of lipid rafts. We have investigated the detergent insolubility of several known proteins present in the glycosphingolipid/cholesterol-rich myelin membrane, using four detergents representing different chemical classes (TX-100, CHAPS, Brij 96 and TX-102), under four conditions: detergent extraction of myelin either at (i) 4°C or (ii) 37°C, or at 4°C after pre-extraction with (iii) saponin or (iv) methyl-β-cyclodextrin (MβCD). Each detergent was different in its ability to solubilize myelin proteins and in the density of the DIGs produced. Brij 96 DIGs floated to a lower density than other detergents tested, possibly representing a subpopulation of DIGs in myelin. DIGs pre-extracted with saponin were denser than DIGs pre-extracted with MβCD. Furthermore, pre-extraction with MβCD solubilized proteolipid protein (known to associate with cholesterol), whereas pre-extraction with saponin did not, suggesting that saponin is less effective as a cholesterol-perturbing agent than is MβCD. These results demonstrate that DIGs isolated by different detergents are not necessarily comparable, and that these detergent-specific DIGs may represent distinct biochemical, and possibly physiological, entities based on the solubilities of specific lipids/proteins in each type of detergent.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1471-4159.2002.00884.x
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