Endocytosis and Vesicle Recycling at a Ribbon Synapse

• DOI: 10.1523/jneurosci.23-10-04092.2003
• Publication Date: 2018-04-13T22:30:28Z
• Authors: Christophe Paillart; Jian Li; Gary Matthews; Peter Sterling
• Keywords: Ribbon synapse

At ribbon synapses, where exocytosis is regulated by graded depolarization, vesicles can fuse very rapidly with the plasma membrane (complete discharge of releasable pool in approximately 200 msec). Vesicles are also retrieved (time constant 1 sec), leading us to wonder whether their retrieval uses an unusual mechanism. To study this, we exposed isolated bipolar neurons from goldfish retina cationized ferritin. This electron-dense marker uniformly decorated cell and was carried into during retrieval. Endocytosis activity-dependent restricted synaptic terminal. The labeling pattern consistent direct large, uncoated endosomes 60-200 nm diameter. Even after extensive activity lasting several minutes, most ferritin remained large present only 10% small that constitute reserve pool. By contrast, brief stimulation at a conventional terminal, did not reside but 63% vesicles. We suggest synapse sustains its rapid retrieving larger "bites" than clathrin-dependent mechanism thought dominate synapses. resulting bud off vesicles, which reenter finally