SPECIFIC ASYMMETRIC FUSION BETWEEN ARTIFICIAL AND BIOLOGICAL MODEL MEMBRANES

Experimental conditions are delineated for specific asymmetric fusion, induced by Ca2+ ions, of vesicles formed from di-n-dodecyl phosphate (DDP) with phosphatidylserine (PS) and dioleoylphosphatidylcholine (DOPC) liposomes as well as with erythrocyte ghost (EG) membranes. Initial rates and extents of fusion were obtained with the resonance energy transfer assay. The merging of the bilayers rather than vesicle aggregation represents the rate-determining step in the overall fusion event. Unexpectedly, asymmetric PS-DDP and DOPC-DDP vesicle fusion does occur below the main phase-transition temperature of the DDP bilayer. At 25 °C and pH 7.4, DDP vesicles fuse with EG membranes more rapidly and efficiently than PS vesicles. The possible relevance of these findings for cell biological and drug-targetting experiments is pointed out. © 1990, American Chemical Society. All rights reserved.