Separation and characterization of late endosomal membrane domains.
Very little is known about the biophysical properties and the lipid or protein composition of membrane domains presumably present in endocytic and biosynthetic organelles. Here we analyzed the membrane composition of late endosomes by suborganellar fractionation in the absence of detergent. We found that the internal membranes of this multivesicular organelle can be separated from the limiting membrane and that each membrane population exhibited a defined composition. Our data also indicated that internal membranes may consist of at least two populations, containing primarily phosphatidylcholine or lysobisphosphatidic acid as major phospholipid, arguing for the existence of significant microheterogeneity within late endosomal membranes. We also found that lysobisphosphatidic acid exhibited unique pH-dependent fusogenic properties, and we speculated that this lipid is an ideal candidate to regulate the dynamic properties of this internal membrane mosaic.
Kobayashi
Toshihide
T
Department of Biochemistry, Sciences II, University of Geneva, 30 Quai E. Ansermet, 1211-Geneva-4, Switzerland.
Beuchat
Marie-Hélène
MH
Chevallier
Julien
J
Makino
Asami
A
Mayran
Nathalie
N
Escola
Jean-Michel
JM
Lebrand
Cecile
C
Cosson
Pierre
P
Kobayashi
Tetsuyuki
T
Gruenberg
Jean
J
D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D011992:Endosomes / Q000737:chemistry / Q000648:ultrastructure*; D005230:Fatty Acids, Nonesterified / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000737:chemistry / Q000648:ultrastructure*; D007668:Kidney; D008246:Lysophospholipids / Q000032:analysis; D008561:Membrane Fusion; D008563:Membrane Lipids / Q000032:analysis*; D050178:Monoglycerides; D010743:Phospholipids / Q000032:analysis*
D005230:Fatty Acids, Nonesterified; D008246:Lysophospholipids; D008563:Membrane Lipids; D050178:Monoglycerides; D010743:Phospholipids; C012786:bis(monoacylglyceryl)phosphate