Fusion of dipalmitoylphosphatidylcholine vesicle membranes induced by concanavalin A.

Bosch, Jürgen; McConnell, Melanie J.

doi:10.1073/pnas.72.11.4409

Cited by 60 publications

(16 citation statements)

References 35 publications

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“…1) make specific contacts with the rot-particle dome to produce or stimulate the "destabilization" conditions (29) required for bilayer fusion. The studies of van der Bosch and McConnell (49), which suggest that protein-to-protein interactions induce lipid phase separations (21,22,46) followed by membrane fusion, are of direct interest in this regard, as is the demonstration by Scheid and Choppin (44) of a direct participation in cell fusion by a specific surface glycoprotein of Sendai virions. Other possibilities are that the fertilization tubule tip contains a specific class of lipid, that the mt-particle dome possesses a lipase activity for that lipid, and that the mt+/mt -specificity of fusion, plus the fusion event itself, results from such an enzymesubstrate interaction (see, in this regard, references 26 and 40).…”

Section: The Fusion Processmentioning

confidence: 99%

Membrane differentiations at sites specialized for cell fusion.

Weiss¹,

Goodenough²,

Goodenough³

1977

The Journal of Cell Biology

104

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Fusion of plasma membranes between Chlamydomonas reinhardtii gametes has been studied by freeze-fracture electron microscopy of unfixed cells. The putative site of cell fusion develops during gametic differentiation and is recognized in thin sections of unmated gametes as a plaque of dense material subjacent to a sector of the anterior plasma membrane (Goodenough, U. W., and R. L. Weiss. 1975. J. Cell Biol. 67"623-637). The overlying membrane proves to be readily recognized in replicas of unmated gametes as a circular region roughly 500 nm in diameter which is relatively free of "regular" plasma membrane particles on both the P and E fracture faces. The morphology of this region is different for mating-type plus (rot § and rot-gametes: the few particles present in the center of the mt § region are distributed asymmetrically and restricted to the P face, while the few particles present in the center of the mt-region are distributed symmetrically in the E face. Each gamete type can be activated for cell fusion by presenting to it isolated flagella of opposite rnt. The activated mt+ gamete generates large expanses of particle-cleared membrane as it forms a long fertilization tubule from the mating structure region. In the activated rot-gamete, the E face of the mating structure region is transformed into a central dome of densely clustered particles surrounded by a particle-cleared zone. When mt § and mt-gametes are mixed together, flagellar agglutination triggers similar activation events, but the tip of each mt § fertilization tubule proceeds to fuse with an activated mt-region. The fusion lip is seen to develop within the particle-dense central dome. We conclude that these mt-particles play an active role in membrane fusion.Cell fusion initiates the sexual process in both lower and higher eukaryotes, but the mechanism(s) by which the participating membranes actually fuse with one another remains largely unknown. Experiments with model membrane systems have established that lipid bilayers are inherently very stable structures (28) which must be "conditioned" by some destabilizing agent or process if they are to fuse with one another (reviewed in reference 29). While a number of such "fusogenic agents" have been identified in vitroincluding certain fatty acids or lipids (1, 2, 25, 27), detergents (8, 26, 40), and ionic or thermal conditions

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Section: The Fusion Processmentioning

confidence: 99%

Membrane differentiations at sites specialized for cell fusion.

Weiss¹,

Goodenough²,

Goodenough³

1977

The Journal of Cell Biology

104

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“…Several model systems for membrane fusion have been developed recently, such as chemicallyinduced fusion of membranes which do not fuse physiologically [7,8], virusinduced cell fusion [9,10], liposome-cell fusion [11--14] and liposome-liposome fusion [15][16][17][18]. As opposed to artificial model systems, tissue fractionation techniques to isolate membranes which have the physiological capacity for fusion have been utilized in the present study.…”

Section: Introductionmentioning

confidence: 99%

Fusion of isolated myoblast plasma membranes. An approach to the mechanism

Dahl

Schudt

Gratzl

1978

Biochimica et Biophysica Acta (BBA) - Biomembranes

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Summary 105Fusion of plasma membranes isolated from myoblasts grown in culture has been investigated.1. Membrane fusion was specifically dependent on Ca 2 + at physiological concentrations. However, at higher concentrations of cations, fusion could be triggered not only by Ca2+, but by Mg2+ and Sr 2 + as weH.2. The amount of fusion was directly proportional to temperature. 3. Fusion was found to depend on the state of maturation of the my oblast membranes.4. Experiments with chemically and enzymatically modified mem branes and with membranes derived from myoblasts grown in the presence of inhibitors of protein biosynthesis suggest the participation of proteinaceous membrane components in the fusion mechanism.

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“…with more packed lipids. The mitogens increase the lipids fluctuations and bilayers defects [23,24], so that aggregation and fusion of the small unilamellar vesicles, as already observed with plant lectine [25] as well as with influenza virus fusion protein [26 and ref. therein], occur.…”

Section: -Discussionmentioning

confidence: 74%

Mitogens-DPPC-vesicles interaction: A spin label ESR study

1993

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Summary. --The electron spin resonance spectroscopy with the spin labelling technique has been used to investigate the interaction of sonicated di-palmitoylphosphatidylcholine (DPPC) small unilamellar vesicles with concanavalin A (Con A), phytohemagglutinin (PHA) and staphylococcal enterotoxin B (SEB) in the temperature range 0-50~ Conventional ESR measurements show that the addition of mitogens to the vesicles suspensions up to the number of mitogens/number of vesicles ratio of 60 increases the orientational degree of order of the lipid molecules in the gel phase and the gel-*liquid-crystalline phase transition temperature. No effects on the liquid-crystalline phase have been observed, also no matter for the mitogen used. The effectiveness results in the order: ConA> SEB > PHA. Saturation transfer-ESR measurements evidence more restricted rotation of the DPPC molecules in the gel phase in the presence of Con A and SEB than in the presence of PHA if compared to pure DPPC-vesicles. The effective rotational correlation time, %, of the spin label 5-SASL results about one order of magnitude higher in the presence of 60 mitogen molecules/vesicle. The ESR findings suggest a mitogen-induced increase in the packing density of lipid bilayers which is attributed to a morphological change from sonicated vesicles, with a small radius of curvature, to a more planar mesophase. Con A is more effective than SEB and PHA in inducing this process. PACS 87.15 -Molecular biophysics.

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Fusion of dipalmitoylphosphatidylcholine vesicle membranes induced by concanavalin A.

Cited by 60 publications

References 35 publications

Membrane differentiations at sites specialized for cell fusion.

Membrane differentiations at sites specialized for cell fusion.

Fusion of isolated myoblast plasma membranes. An approach to the mechanism

Mitogens-DPPC-vesicles interaction: A spin label ESR study

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