Unbiased quantitative proteomics of lipid rafts reveals high specificity for signaling factors.
Membrane lipids were once thought to be homogenously distributed in the 2D surface of a membrane, but the lipid raft theory suggests that cholesterol and sphingolipids partition away from other membrane lipids. Lipid raft theory further implicates these cholesterol-rich domains in many processes such as signaling and vesicle traffic. However, direct characterization of rafts has been difficult, because they cannot be isolated in pure form. In the first functional proteomic analysis of rafts, we use quantitative high-resolution MS to specifically detect proteins depleted from rafts by cholesterol-disrupting drugs, resulting in a set of 241 authentic lipid raft components. We detect a large proportion of signaling molecules, highly enriched versus total membranes and detergent-resistant fractions, which thus far biochemically defined rafts. Our results provide the first large-scale and unbiased evidence, to our knowledge, for the connection of rafts with signaling and place limits on the fraction of plasma membrane composed by rafts.
Center for Experimental BioInformatics, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
Leonard J
LJ
Foster
Carmen L
CL
De Hoog
Matthias
M
Mann
D002458:Cell Fractionation; D002499:Centrifugation, Density Gradient; D003470:Culture Media; D003902:Detergents / Q000494:pharmacology; D005372:Filipin / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007930:Leucine / Q000378:metabolism; D021962:Membrane Microdomains / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics; D009761:Nystatin / Q000494:pharmacology; D020543:Proteome; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
D003470:Culture Media; D003902:Detergents; D008565:Membrane Proteins; D020543:Proteome; D009761:Nystatin; D005372:Filipin; D007930:Leucine