Abstract
Multilamellar phospholipid vesicles are introduced into the cis compartment on one side of a planar phospholipid bilayer membrane. The vesicles contain a water-soluble fluorescent dye trapped in the aqueous phases between the lamellae. If a vesicle containing n lamellae fuses with a planar membrane, an n-1 lamellar vesicle should be discharged into the opposite trans compartment, where it would appear as a discernible fluorescent particle. Thus, fusion events can be assayed by counting the number of fluorescent particles appearing in the trans compartment. In the absence of divalent cation, fusion does not occur, even after vesicles have been in the cis compartment for 40 min. When CaCl2 is introduced into the cis compartment to a concentration of greater than or equal to 20 mM, fusion occurs within the next 20 min; it generally ceases thereafter because of vesicle aggregation in the cis compartment. With approximately 3 x 10(8) vesicles/cm3 in the cis compartment, about 25-50 fusion events occur following CaCl2 addition. The discharge of vesicular contents across the planar membrane is the most convincing evidence of vesicle-membrane fusion and serves as a model for that ubiquitous biological phenomenon--exocytosis.
Full Text
The Full Text of this article is available as a PDF (587.8 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Cohen F. S., Zimmerberg J., Finkelstein A. Fusion of phospholipid vesicles with planar phospholipid bilayer membranes. II. Incorporation of a vesicular membrane marker into the planar membrane. J Gen Physiol. 1980 Mar;75(3):251–270. doi: 10.1085/jgp.75.3.251. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cohen J. A., Moronne M. M. Interaction of charged lipid vesicles with planar bilayer lipid membranes: detection by antibiotic membrane probes. J Supramol Struct. 1976;5(3):409–416. doi: 10.1002/jss.400050313. [DOI] [PubMed] [Google Scholar]
- Friend D. S., Orci L., Perrelet A., Yanagimachi R. Membrane particle changes attending the acrosome reaction in guinea pig spermatozoa. J Cell Biol. 1977 Aug;74(2):561–577. doi: 10.1083/jcb.74.2.561. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lawson D., Raff M. C., Gomperts B., Fewtrell C., Gilula N. B. Molecular events during membrane fusion. A study of exocytosis in rat peritoneal mast cells. J Cell Biol. 1977 Feb;72(2):242–259. doi: 10.1083/jcb.72.2.242. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Martin F. J., MacDonald R. C. Phospholipid exchange between bilayer membrane vesicles. Biochemistry. 1976 Jan 27;15(2):321–327. doi: 10.1021/bi00647a013. [DOI] [PubMed] [Google Scholar]
- Moore M. R. Fusion of liposomes containing conductance probes with black lipid films. Biochim Biophys Acta. 1976 Apr 5;426(4):765–771. doi: 10.1016/0005-2736(76)90144-9. [DOI] [PubMed] [Google Scholar]
- Palade G. Intracellular aspects of the process of protein synthesis. Science. 1975 Aug 1;189(4200):347–358. doi: 10.1126/science.1096303. [DOI] [PubMed] [Google Scholar]
- Papahadjopoulos D., Vail W. J., Pangborn W. A., Poste G. Studies on membrane fusion. II. Induction of fusion in pure phospholipid membranes by calcium ions and other divalent metals. Biochim Biophys Acta. 1976 Oct 5;448(2):265–283. doi: 10.1016/0005-2736(76)90241-8. [DOI] [PubMed] [Google Scholar]
- Pinto da Silva P., Nogueira M. L. Membrane fusion during secretion. A hypothesis based on electron microscope observation of Phytophthora Palmivora zoospores during encystment. J Cell Biol. 1977 Apr;73(1):161–181. doi: 10.1083/jcb.73.1.161. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Satir B., Schooley C., Satir P. Membrane fusion in a model system. Mucocyst secretion in Tetrahymena. J Cell Biol. 1973 Jan;56(1):153–176. doi: 10.1083/jcb.56.1.153. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Weinstein J. N., Yoshikami S., Henkart P., Blumenthal R., Hagins W. A. Liposome-cell interaction: transfer and intracellular release of a trapped fluorescent marker. Science. 1977 Feb 4;195(4277):489–492. doi: 10.1126/science.835007. [DOI] [PubMed] [Google Scholar]