Diversity of raft-like domains in late endosomes.
BACKGROUND
Late endosomes, the last sorting station in the endocytic pathway before lysosomes, are pleiomorphic organelles composed of tubular elements as well as vesicular regions with a characteristic multivesicular appearance, which play a crucial role in intracellular trafficking. Here, we have investigated whether, in addition to these morphologically distinguishable regions, late endosomal membranes are additionally sub-compartmentalized into membrane microdomains.


RESULTS
Using sub-organellar fractionation techniques, both with and without detergents, combined with electron microscopy, we found that both the limiting membrane of the organel and the intraluminal vesicles contain raft-type membrane domains. Interestingly, these differentially localized domains vary in protein composition and physico-chemical properties.


CONCLUSIONS
In addition to the multivesicular organization, we find that late endosomes contain cholesterol rich microdomains both on their limiting membrane and their intraluminal vesicles that differ in composition and properties. Implications of these findings for late endosomal functions are discussed.
Sobo
Komla
K
Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland.
Chevallier
Julien
J
Parton
Robert G
RG
Gruenberg
Jean
J
van der Goot
F Gisou
FG
D000818:Animals; D002451:Cell Compartmentation; D002478:Cells, Cultured; D002855:Chromatography, Thin Layer; D006224:Cricetinae; D011992:Endosomes / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D012995:Solubility; D013347:Subcellular Fractions / Q000378:metabolism