Effect of transbilayer phospholipid distribution on erythrocyte fusion.
Phospholipid packing has been suggested as a relevant variable in the control of membrane fusion events. To test this possibility in a model system, a comparison was made of the fusability of erythrocytes with a normal asymmetric transbilayer distribution of plasma membrane phospholipids (tightly packed exterior lipids) and erythrocytes with a symmetric transbilayer distribution of phospholipids (more loosely packed exterior lipids), using polyethylene glycol as fusogen. Not only were lipid-symmetric cells more readily fused, but fusions of mixtures of lipid-symmetric and lipid-asymmetric cells indicated that both fusing partners must have a symmetric distribution for fusion to be enhanced. Lipid-symmetric cells may fuse more readily because loose packing of the exterior lipids enhances hydrophobic interactions between cells. Alternatively, enhanced membrane fluidity may facilitate intramembranous particle clustering, previously implicated as a potentiator of fusion. Finally, exposure of phosphatidylserine on the surface of lipid-symmetric erythrocytes may be responsible for their enhanced fusion.
Tullius
E K
EK
Department of Molecular and Cell Biology, Pennsylvania State University, University Park 16802.
Williamson
P
P
Schlegel
R A
RA
D002118:Calcium / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008051:Lipid Bilayers / Q000097:blood*; D008561:Membrane Fusion / Q000187:drug effects; D010743:Phospholipids / Q000097:blood; D011092:Polyethylene Glycols / Q000494:pharmacology
D008051:Lipid Bilayers; D010743:Phospholipids; D011092:Polyethylene Glycols; D002118:Calcium