Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The phospholipids distribution across red cell membrane bilayer is asymmetrical. Phosphatidylcholine (PC) and sphingomyelin (SM) are predominantly present in the outer, and phosphatidylserine (PS) and phosphatidylethanolamine (PE) are predominantly present on the cytoplasmic side of the red cell membrane. The present study reports the effect of fatty acid peroxidation on the organization of PS and PE in human red cells using a nonpermeable Bee Venom phospholipase-A2 which specifically hydrolyzes outer bilayer lipids. Lipid peroxidation in the red cell membranes was accomplished by exposing cells to hydrogen peroxide. This treatment resulted in a significant movement of PS and PE from inner bilayer to outer bilayer, which had a highly positive correlation with the concentration of malonyldialdehyde generated in the red cells. Antioxidant vitamin E abolished the effects of peroxide treatment on fatty acid peroxidation and red cell membrane lipid organization. Thus, lipid peroxidative damage can disturb organization of phospholipids in the membrane bilayer of human red cells.
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PMID:Vitamin E and stabilization of membrane lipid organization in red blood cells with peroxidative damage. 667 17

Exosomes are small vesicles secreted from multivesicular bodies, which are able to stimulate the immune system leading to tumour cell eradication. We have analysed lipids of exosomes secreted either upon stimulation from rat mast cells (RBL-2H3 cells), or constitutively from human dendritic cells. As compared with parent cells, exosomes displayed an enrichment in sphingomyelin, but not in cholesterol. Phosphatidylcholine content was decreased, but an enrichment was noted in disaturated molecular species as in phosphatidylethanolamines. Lyso(bis)phosphatidic acid was not enriched in exosomes as compared with cells. Fluorescence anisotropy demonstrated an increase in exosome-membrane rigidity from pH 5 to 7, suggesting their membrane reorganization between the acidic multivesicular body compartment and the neutral outer cell medium. NMR analysis established a bilayer organization of exosome membrane, and ESR studies using 16-doxyl stearic acid demonstrated a higher flip-flop of lipids between the two leaflets as compared with plasma membrane. In addition, the exosome membrane exhibited no asymmetrical distribution of phosphatidylethanolamines. Therefore exosome membrane displays a similar content of the major phospholipids and cholesterol, and is organized as a lipid bilayer with a random distribution of phosphatidylethanolamines. In addition, we observed tight lipid packing at neutral pH and a rapid flip-flop between the two leaflets of exosome membranes. These parameters could be used as a hallmark of exosomes.
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PMID:Mast cell- and dendritic cell-derived exosomes display a specific lipid composition and an unusual membrane organization. 1496 43