We have examined the kinetics by which FM1-43 escapes from individual synaptic vesicles during exocytosis at hippocampal boutons. Two populations of exocytic events were observed; small amplitude events that lose dye slowly, which made up more than half of all events, and faster, larger amplitude events with a fluorescence intensity equivalent to single stained synaptic vesicles. These populations of destaining events are distinct in both brightness and kinetics, suggesting that they result from two distinct modes of exocytosis. Small amplitude events show tightly clustered rate constants of dye release, whereas larger events have a more scattered distribution. Kinetic analysis of the association and dissociation of FM1-43 with membranes, in combination with a simple pore permeation model, indicates that the small, slowly destaining events may be mediated by a narrow ∼1-nm fusion pore.
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14 March 2005
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March 14 2005
Two modes of exocytosis at hippocampal synapses revealed by rate of FM1-43 efflux from individual vesicles
David A. Richards,
David A. Richards
Department of Physiology, University of Wisconsin-Madison, Madison, WI 53706
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Jihong Bai,
Jihong Bai
Department of Physiology, University of Wisconsin-Madison, Madison, WI 53706
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Edwin R. Chapman
Edwin R. Chapman
Department of Physiology, University of Wisconsin-Madison, Madison, WI 53706
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David A. Richards
Department of Physiology, University of Wisconsin-Madison, Madison, WI 53706
Jihong Bai
Department of Physiology, University of Wisconsin-Madison, Madison, WI 53706
Edwin R. Chapman
Department of Physiology, University of Wisconsin-Madison, Madison, WI 53706
Correspondence to E.R. Chapman: [email protected]
D.A. Richards's present address is Dept. of Cell Biology, Neurobiology and Anatomy, University of Cincinnati, Vontz Center for Molecular Medicine, Cincinnati, OH 45267.
Abbreviations used in this paper: PC, 1,2-dioleoyl-sn-glycero-3-phosphocholine; PE, 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine; SV, synaptic vesicle.
Received:
July 23 2004
Accepted:
January 20 2005
Online ISSN: 1540-8140
Print ISSN: 0021-9525
The Rockefeller University Press
2005
J Cell Biol (2005) 168 (6): 929–939.
Article history
Received:
July 23 2004
Accepted:
January 20 2005
Citation
David A. Richards, Jihong Bai, Edwin R. Chapman; Two modes of exocytosis at hippocampal synapses revealed by rate of FM1-43 efflux from individual vesicles . J Cell Biol 14 March 2005; 168 (6): 929–939. doi: https://doi.org/10.1083/jcb.200407148
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