Stimulated exocytosis of endosomes in goldfish retinal bipolar neurons
- 1Department of Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, SHM-B114, New Haven, CT 06520, USA2Vollum Institute, 3181 SW Sam Jackson Park Road, Portland, OR 97212, USA
- Corresponding author D. Zenisek: Department of Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar St, SHM-B114, New Haven, CT 06520, USA. Email: david.zenisek{at}yale.edu
Abstract
After exocytosis, synaptic vesicle components are selectively retrieved by clathrin-mediated endocytosis and then re-used in future rounds of transmitter release. Under some conditions, synaptic terminals in addition perform bulk endocytosis of large membranous sacs. Bulk endocytosis is less selective than clathrin-mediated endocytosis and probably internalizes components normally targeted to the plasma membrane. Nonetheless, this process plays a major role in some tonic ribbon-type synapses, which release neurotransmitter for prolonged periods of time. We show here, that large endosomes formed after strong and prolonged stimulation undergo stimulated exocytosis in retinal bipolar neurons. The result suggests how cells might return erroneously internalized components to the plasma membrane, and also demonstrates that synaptic vesicles are not the only neuronal organelle that stains with styryl dyes and undergoes stimulated exocytosis.
Footnotes
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(Resubmitted 16 July 2007; accepted after revision 3 September 2007; first published online 6 September 2007)
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This paper has online supplemental material.
- 2007 The Authors. Journal compilation © 2007 The Physiological Society
