Co-reporter:Roger J. Morris;Angela Jen;Alice Warley
Journal of Neurochemistry 2011 Volume 116( Issue 5) pp:671-677
Publication Date(Web):
DOI:10.1111/j.1471-4159.2010.07076.x
J. Neurochem. (2011) 116, 671–678.
Abstract
This review assesses problems that confound attempts to isolate ‘raft’ domains from cell membranes, focusing in particular upon the isolation of detergent resistant membrane (DRM). Despite its widespread use, this technique is rightly viewed with skepticism by many membrane biochemists and biophysics for reasons that include the inability to isolate DRMs at 37°C, the temperature at which their lipids are supposed to be ordered and so exclude detergents. If solubilization is done in an ionic buffer that preserves the lamellar phase of the metastable inner leaflet lipids, DRMs can readily be isolated at 37°C, and these have many properties expected of lipid rafts. However, to date these DRMs have remained somewhat larger than current concepts of rafts. We describe an adaptation of this method that purifies nano–meso scale DRMs, and could be a significant step towards purifying the membrane of individual ‘rafts’.
Co-reporter:Roger J. Morris
FEBS Letters (3 May 2010) Volume 584(Issue 9) pp:1665-1669
Publication Date(Web):3 May 2010
DOI:10.1016/j.febslet.2009.11.017
The phospholipids of the inner and outer leaflets of the plasma membrane face chemically very different environments, and are specialized to serve different needs. While lipids of the outer leaflet are inherently stable in a lamellar (bilayer) phase, the main lipid of the inner layer, phosphatidylethanolamine (PE), does not form a lamellar phase unless evenly mixed with phosphatidylserine (PS−). This mixture can be readily perturbed by factors that include an influx of Ca2+ that chelates the negatively charged PS−, thereby destabilizing PE. The implications of this metastability of the inner leaflet for vesicular trafficking, and experimentally for the isolation of detergent-resistant membrane domains (DRMs) at physiological temperature, are considered.