Figure 8.

Single fusion events are unchanged by mutation or deletion of Munc18-1. Kinetics of single fusion events, assayed by carbon fiber amperometry, during sustained stimulation by extracellular K⁺. A, Amperometric spikes (top) from a munc18-1 ^−/− cell expressing Munc18-1. Note the prespike foot in the expanded trace (bottom). B, Total charge (Q) of the spikes recorded from munc18-1 −/−, +/−, or +/+ cells, or −/− cells expressing different Munc18 constructs. Shown is the mean of cell medians. For statistics of other parameters, see Table 1. C, Comparison of Munc18-1 R39C with Munc18-1 expressed in either munc18-1 ^−/− mouse cells or bovine cells.