Transmembrane distribution of sterol in the human erythrocyte.
The transbilayer cholesterol distribution of human erythrocytes was examined by two independent techniques, quenching of dehydroergosterol fluorescence and fluorescence photobleaching of NBD-cholesterol. Dehydroergosterol in conjunction with leaflet selective quenching showed that, at equilibrium, 75% of the sterol was localized to the inner leaflet of resealed erythrocyte ghosts. NBD-cholesterol and fluorescence photobleaching displayed two diffusion values in both resealed ghosts and intact erythrocytes. The fractional contribution of the fast and slow diffusion constants of NBD-labelled cholesterol represent its inner and outer leaflet distribution. At room temperature the plasma membrane inner leaflet of erythrocyte ghosts as well as intact erythrocytes cells contained 78% of the plasma membrane sterol. The erythrocyte membrane transbilayer distribution of sterol was independent of temperature. In conclusion, dehydroergosterol and NBD-cholesterol data are consistent with an enrichment of cholesterol in the inner leaflet of the human erythrocyte.
Schroeder
F
F
Department of Pharmacology and Cell Biophysics, University of Cincinnati Medical Center, OH.
Nemecz
G
G
Wood
W G
WG
Joiner
C
C
Morrot
G
G
Ayraut-Jarrier
M
M
Devaux
P F
PF
D002784:Cholesterol / Q000031:analogs & derivatives / Q000737:chemistry*; D004161:Diphenylhexatriene / Q000737:chemistry; D004875:Ergosterol / Q000031:analogs & derivatives* / Q000737:chemistry; D004910:Erythrocyte Membrane / Q000737:chemistry*; D004912:Erythrocytes / Q000737:chemistry; D005453:Fluorescence; D006801:Humans; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000737:chemistry; D010741:Phospholipases A / Q000378:metabolism; D014302:Trinitrobenzenesulfonic Acid / Q000494:pharmacology
D008051:Lipid Bilayers; D008081:Liposomes; D010714:Phosphatidylethanolamines; C010905:dehydroergosterol; D004161:Diphenylhexatriene; D014302:Trinitrobenzenesulfonic Acid; D002784:Cholesterol; D010741:Phospholipases A; D004875:Ergosterol