title: Separation and characterization of late endosomal membrane domains.
abstract: 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.
authors.affiliation: Department of Biochemistry, Sciences II, University of Geneva, 30 Quai E. Ansermet, 1211-Geneva-4, Switzerland.
authors.forename: Toshihide
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Beuchat
authors.forename: Julien
authors.initials: J
authors.lastname: Chevallier
authors.forename: Asami
authors.initials: A
authors.lastname: Makino
authors.forename: Nathalie
authors.initials: N
authors.lastname: Mayran
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Escola
authors.forename: Cecile
authors.initials: C
authors.lastname: Lebrand
authors.forename: Pierre
authors.initials: P
authors.lastname: Cosson
authors.forename: Tetsuyuki
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Jean
authors.initials: J
authors.lastname: Gruenberg
mesh_terms: 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*
chemical_list: D005230:Fatty Acids, Nonesterified; D008246:Lysophospholipids; D008563:Membrane Lipids; D050178:Monoglycerides; D010743:Phospholipids; C012786:bis(monoacylglyceryl)phosphate