Ca2+-induced fusion of phospholipid vesicles monitored by mixing of aqueous contents

  title={Ca2+-induced fusion of phospholipid vesicles monitored by mixing of aqueous contents},
  author={J. Wilschut and D. Papahadjopoulos},
Ca2+ has a central role in various cellular phenomena involving membrane fusion1–3. However, little is known about the mechanisms involved. Model membrane systems such as phospholipid vesicles have been used extensively to study the mechanism of membrane fusion at the molecular level4. For example, phosphatidylserine (PS) vesicles have been shown to undergo massive aggregation and structural rearrangements on addition of Ca2+, with eventual formation of large cochleate structures5–8. Although… Expand
Mechanisms of Membrane Fusion in Acidic Lipid-Cation Systems
Since the original discovery that Ca+2 converts small vesicles of phosphatidylserine into large sheets of spirally-wrapped membrane (1), the use of acidic lipid-divalent cation systems as models ofExpand
Studies on the mechanism of membrane fusion: kinetics of calcium ion induced fusion of phosphatidylserine vesicles followed by a new assay for mixing of aqueous vesicle contents.
This work has studied the Ca2+-induced fusion of small or large unilamellar vesicles (SUV or LUV, respectively) composed of phosphatidylserine (PS), and found that at high vesicle concentrations (and at relatively low Ca2- concentrations) aggregation may proceed faster than fusion. Expand
Ca2+-induced fusion of cardiolipin/phosphatidylcholine vesicles monitored by mixing of aqueous contents.
The kinetics of Ca2+-induced fusion of large (0.1 micrometer) unilamellar cardiolipin/phosphatidylcholine (1:1) vesicles have been investigated by continuous monitoring of the mixing of the aqueousExpand
Ca2+-induced fusion of phosphatidylserine vesicles: mass action kinetic analysis of membrane lipid mixing and aqueous contents mixing.
We have investigated the initial kinetics of Ca2+-induced aggregation and fusion of phosphatidylserine large unilamellar vesicles at 3, 5 and 10 mM Ca2+ and 15, 25 and 35 degrees C, utilizing theExpand
Control of membrane fusion by phospholipid head groups. I. Phosphatidate/phosphatidylinositol specificity.
The results indicated striking differences with respect to the fusion capacity of the different vesicles and the possible role of the metabolic interconversion of phosphatidylinositol to phosphatidate as an on-off control system for membrane fusion phenomena involved in secretion is discussed. Expand
A mechanism of divalent ion-induced phosphatidylserine membrane fusion.
  • S. Ohki
  • Chemistry, Medicine
  • Biochimica et biophysica acta
  • 1982
It is deduced that the main cause of divalent cation-induced membrane fusion of phosphatidylserine membranes is the degree of increased hydrophobicity (surface tension increase) of the membrane surface, which results from the binding of cations to acidic phospholipid membrane surfaces. Expand
Modulation of membrane fusion by membrane fluidity: temperature dependence of divalent cation induced fusion of phosphatidylserine vesicles.
We have investigated the temperature dependence of the fusion of phospholipid vesicles composed of pure bovine brain phosphatidylserine (PS) induced by Ca2+ or Mg2+. Aggregation of the vesicles wasExpand
Abstract The relative kinetics of intermixing and release of liposome aqueous contents during Ca 2+ -induced membrane fusion has been investigated. Fusion was monitored by the Tb-dipicolinic acidExpand
Studies on the mechanism of membrane fusion. Role of head-group composition in calcium- and magnesium-induced fusion of mixed phospholipid vesicles.
It is suggested that the role of phospholipids in membrane fusion is related to their ability to form dehydrated intermembrane complexes with divalent cations. Expand
Membrane fusion: lipid vesicles as a model system.
Current views on the way membrane proteins may induce fusion under physiological conditions also emphasize the notion of local surface dehydration and perturbation of lipid packing, possibly through penetration of apolar amino acid segments into the hydrophobic membrane interior. Expand


Does Ca2+ cause fusion or lysis of unilamellar lipid vesicles?
Experimental support for vesicle lysis is reported, based on the redistribution of a marker for the aqueous phase between vesicles and the external compartment on exposure to divalent cations, which suggests that vESicles cannot approach closely enough to fuse and supports the notion that Ca2+ may initiate vesic lysis and reassembly. Expand
Studies on membrane fusion. III. The role of calcium-induced phase changes.
It is concluded that the key event leading to vesicle membrane fusion is the isothermic phase change induced by the bivalent metals. Expand
Studies on the mechanism of membrane fusion: evidence for an intermembrane Ca2+-phospholipid complex, synergism with Mg2+, and inhibition by spectrin.
It is proposed that the unique PS/Ca complex, which involves close apposition of vesicle membranes, is an intermembrane "trans" complex that is a key step for the resultant phase transition and fusion of PS vesicles. Expand
Calcium-induced aggregation and fusion of mixed phosphatidylcholine-phosphatidic acid vesicles as studied by 31P NMR.
The data suggest that Ca2+-induced lateral phase separations make the bilayer more susceptible to fusion. Expand
The role of calcium in fusion of artificial vesicles.
Small phospholipid vesicles (liposomes) fuse upon calcium addition as demonstrated by electron microscopy, light absorbance increases, and mixing of original liposome contents within the boundariesExpand
Fusion of phosphatidic acid-phosphatidylcholine mixed lipid vesicles.
The controllable and concerted fusions make the phosphatidic acid system suitable for further mechanistic studies and indicative of concerted two vesicles and multiple vesicle fusions. Expand
Cochleate lipid cylinders: formation by fusion of unilamellar lipid vesicles.
The name cochleate lipid cylinders is suggested for the spiral structures formed by fusion of unilamellar vesicles into large sheets which fold spirally to form cylinders in phosphatidylserine preparations. Expand
Specificity of Ca2+ and Mg2+ binding to phosphatidylserine vesicles and resultant phase changes of bilayer membrane structure.
Differences in the interaction of Ca2+ and Mg2+ with phosphatidylserine vesicles were revealed by binding studies, differential scanning calorimetry and X-ray diffraction, and analysis of the binding data showed thatCa2+ had a ten-fold greater intrinsic binding constant for phosphatidsserine. Expand
Liposome--lymphocyte interaction: saturable sites for transfer and intracellular release of liposome contents.
The water-soluble dye 6-carboxyfluorescein was trapped in the internal aqueous compartments of small sonicated dioleoyl lecithin vesicles and used to assess the kinetics of transfer of vesicleExpand
Calcium and the Secretory Process
The role of Cyclic AMP in the Secretory Process, and the nature of the Role of Calcium in Secretion, are described. Expand