Micromolar Ca2+ stimulates fusion of lipid vesicles with planar bilayers containing a calcium-binding protein

Joshua Zimmerberg, Fredric S. Cohen, Alan Finkelstein

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Fusion of phospholipid vesicles with a planar phospholipid bilayer membrane that contains a calcium-binding protein appears to mimic the essential aspects of cytoplasmic-vesicle fusion with plasma membranes (exocytosis) in that (i) there is a low basal rate of fusion in the absence of Ca2+, (ii) this basal rate is enormously increased by micromolar (∼ 10 μM) amounts of Ca2+, and (iii) this rate is not increased by millimolar Mg 2+. Essential to this process is an osmotic gradient across the planar membrane, with the side containing the vesicles hyperosmotic to the opposite side. Similar osmotic gradients or their equivalent may be crucial for biological fusion events.

Original languageEnglish (US)
Pages (from-to)906-908
Number of pages3
Issue number4472
Publication statusPublished - Jan 1 1980


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