TY - JOUR
T1 - Membrane fusion and molecular segregation in phospholipid vesicles
AU - Papahadjopoulos, D.
AU - Poste, G.
AU - Schaeffer, B. E.
AU - Vail, W. J.
N1 - Funding Information:
This work was supportedb y grantsf rom the National Instituteso f Health No. GM-18921-02(D .P.) and CA-13393-01( G.P.). We thank Messrs T. Isac and D. Grahama nd MrsR . Lazo for valuablete chnicaal ssistancaen d Mr Mark Cowden for the preparatioonf [3H]dipalmitoylphosphatidylcholine.
PY - 1974/5/30
Y1 - 1974/5/30
N2 - Fusion between vesicles prepared from individual or mixed phospholipid species was demonstrated by ultracentrifugation and gel-filtration techniques, electron microscopy and differential scanning calorimetry. Variation of the chemical composition of the vesicles permitted evaluation of the effect of surface charge, Ca2+, fluidity and the presence of cholesterol on the fusion reaction and the segregation of lipid species within fused vesicles. Extensive fusion occurred between negatively charged phosphatidylserine vesicles incubated in the presence of CaCl2 (> 1 mM) and in vesicles prepared from greater than 50% phosphatidylserine in phosphatidylcholine in the presence of CaCl2 (> 4 mM) and albumin (0.1 mg/ml). Neutral phosphatidylcholine vesicles showed only a limited capacity to fuse. Vesicles containing lipids that were in a liquid-crystalline state were more susceptible to fusion than vesicles composed of lipids that were in the solid phase at experimental temperatures. Incorporation of equimolar amounts of cholesterol into vesicles composed of lipids in a liquid-crystalline state suppressed their ability to fuse. Calorimetric measuremens revealed Ca2+ induced segregation of individual lipids to form separate domains within the vesicle membrane (phase separation). The relationship of fusion between vesicles and fusion occurring in natural membranes was discussed.
AB - Fusion between vesicles prepared from individual or mixed phospholipid species was demonstrated by ultracentrifugation and gel-filtration techniques, electron microscopy and differential scanning calorimetry. Variation of the chemical composition of the vesicles permitted evaluation of the effect of surface charge, Ca2+, fluidity and the presence of cholesterol on the fusion reaction and the segregation of lipid species within fused vesicles. Extensive fusion occurred between negatively charged phosphatidylserine vesicles incubated in the presence of CaCl2 (> 1 mM) and in vesicles prepared from greater than 50% phosphatidylserine in phosphatidylcholine in the presence of CaCl2 (> 4 mM) and albumin (0.1 mg/ml). Neutral phosphatidylcholine vesicles showed only a limited capacity to fuse. Vesicles containing lipids that were in a liquid-crystalline state were more susceptible to fusion than vesicles composed of lipids that were in the solid phase at experimental temperatures. Incorporation of equimolar amounts of cholesterol into vesicles composed of lipids in a liquid-crystalline state suppressed their ability to fuse. Calorimetric measuremens revealed Ca2+ induced segregation of individual lipids to form separate domains within the vesicle membrane (phase separation). The relationship of fusion between vesicles and fusion occurring in natural membranes was discussed.
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U2 - 10.1016/0005-2736(74)90175-8
DO - 10.1016/0005-2736(74)90175-8
M3 - Article
C2 - 4859411
AN - SCOPUS:0016151537
SN - 0005-2736
VL - 352
SP - 10
EP - 28
JO - Biochimica et Biophysica Acta - Biomembranes
JF - Biochimica et Biophysica Acta - Biomembranes
IS - 1
ER -