Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 3 of 3
Full-Text Articles in Dentistry
Fusion Of Phospholipid Vesicles Arrested By Quick-Freezing. The Question Of Lipidic Particles As Intermediates In Membrane Fusion, E. L. Bearer, Nejat Düzgüneş, Daniel S. Friend, Demetrios Papahadjopoulos
Fusion Of Phospholipid Vesicles Arrested By Quick-Freezing. The Question Of Lipidic Particles As Intermediates In Membrane Fusion, E. L. Bearer, Nejat Düzgüneş, Daniel S. Friend, Demetrios Papahadjopoulos
All Dugoni School of Dentistry Faculty Articles
We have examined the early events in Ca2+-induced fusion of large (0.2 μm diameter) unilamellar cardiolipin/phosphatidylcholine and phosphatidylserine/phosphatidylethanolamine vesicles by quick-freezing freeze-fracture electron microscopy, eliminating the necessity of using glycerol as a cryoprotectant. Freeze-fracture replicas of vesicle suspensions frozen after 1-2 s of stimulation revealed that the majority of vesicles had already undergone membrane fusion, as evidenced by dumbbell-shaped structures and large vesicles. In the absence of glycerol, lipidic particles or the hexagonal HII phase, which have been proposed to be intermediate structures in membrane fusion, were not observed at the sites of fusion. Lipidic particles were evident in less …
Modulation Of Membrane Fusion By Calcium-Binding Proteins, K. Hong, Nejat Düzgüneş, Demetrios Papahadjopoulos
Modulation Of Membrane Fusion By Calcium-Binding Proteins, K. Hong, Nejat Düzgüneş, Demetrios Papahadjopoulos
All Dugoni School of Dentistry Faculty Articles
The effects of several Ca2+-binding proteins (calmodulin, prothrombin, and synexin) on the kinetics of Ca2+-induced membrane fusion were examined. Membrane fusion was assayed by following the mixing of aqueous contents of phospholipid vesicles. Calmodulin inhibited slightly the fusion of phospholipid vesicles. Bovine prothrombin and its proteolytic fragment 1 had a strong inhibitory effect on fusion. Depending on the phospholipid composition, synexin could either facilitate or inhibit Ca2+-induced fusion of vesicles. The effects of synexin were Ca2+ specific. 10 microM Ca2+ was sufficient to induce fusion of vesicles composed of phosphatidic acid/phosphatidylethanolamine (1:3) in the presence of synexin and 1 mM …
Synexin Facilitates Fusion Of Specific Phospholipid Membranes At Divalent Cation Concentrations Found Intracellularly., K. Hong, Nejat Düzgüneş, R. Ekerdt, Demetrios Papahadjopoulos
Synexin Facilitates Fusion Of Specific Phospholipid Membranes At Divalent Cation Concentrations Found Intracellularly., K. Hong, Nejat Düzgüneş, R. Ekerdt, Demetrios Papahadjopoulos
All Dugoni School of Dentistry Faculty Articles
The effect of synexin (an adrenal medullary protein) on the kinetics of Ca2+- and Mg2+-mediated membrane fusion was examined. Membrane fusion was studied by monitoring intermixing of the aqueous contents of phospholipid vesicles. Synexin facilitated Ca2+-mediated, but not Mg2+-mediated, fusion of phosphatidate/phosphatidylethanolamine (1:3) and phosphatidate/phosphatidylserine/phosphatidylethanolamine/cholesterol (1:2:3:2) vesicles. The threshold concentration of Ca2+ for fusion was decreased to approximately equal to 10 microM in the presence of synexin at 6 micrograms/ml and 1.5 mM Mg2+ in vesicle suspensions containing 50 microM lipid. This effect of synexin was drastically inhibited by including 25% phosphatidylcholine (mol/mol) in the vesicle membrane. It is proposed …