Fusion of a vesicle with the cell membrane opens a pore that releases transmitter to the extracellular space1,2,3. The pore can either dilate fully so that the vesicle collapses completely, or close rapidly to generate ‘kiss-and-run’ fusion1,2,4,5,6,7. The size of the pore determines the release rate2. At synapses, the size of the fusion pore is unclear, ‘kiss-and-run’ remains controversial8,9,10,11,12,13,14,15, and the ability of ‘kiss-and-run’ fusion to generate rapid synaptic currents16,17 is questionable18. Here, by recording fusion pore kinetics during single vesicle fusion, we found both full collapse and ‘kiss-and-run’ fusion at calyx-type synapses. For full collapse, the initial fusion pore conductance (Gp) was usually >375 pS and increased rapidly at ≥299 pS ms–1. ‘Kiss-and-run’ fusion was seen as a brief capacitance flicker (<2 s) with Gp >288 pS for most flickers, but within 15–288 pS for the remaining flickers. Large Gp (>288 pS) might discharge transmitter rapidly and thereby cause rapid synaptic currents, whereas small Gp might generate slow and small synaptic currents. These results show that ‘kiss-and-run’ fusion occurs at synapses and that it can generate rapid postsynaptic currents, and suggest that various fusion pore sizes help to control the kinetics and amplitude of synaptic currents.
Access optionsAccess options
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
We thank V. Klyachko and M. Lindau for technical guidance on cell-attached recordings. We thank M. Lindau for the software for data analysis. We thank J. Diamond, W. Wu, L. Xue, W. Grimes, M. Diaz-Bustamante and B. McNeil for help with simulation and data analysis. We thank J. Diamond, D. Nees, K. Paradiso and J. Xu for comments on the manuscript. This work was supported by the National Institute of Neurological Disorders and Stroke Intramural Research Program.
This file contains 8 sections: I) The debate of 'kiss-and-run' at synapses, II) Capacitance up-step frequency depends on calcium, III) The capacitance up-step or flicker was not caused by the capacitance artifact observed at the whole-cell mode, IV) Switch from the cell-attached to the whole-cell mode, V) Capacitance flickers reflect single vesicle fusion and retrieval, VI) Non-flicker up-steps with a small initial fusion pore conductance, VII) Fusion pore size affects the rate of transmitter release and thus the time course and the amplitude of synaptic currents, and VIII) Methods. This file also contains Supplementary Figures 1–10 and Supplementary Table 1.