Figure 6.

Munc13-4 regulates the start of exocytosis and the size of the steps in C_m. A, representative C_m differentials from C_m traces shown in Fig. 5A. 0, time of cell access; arrowheads, first C_m differential ≥8 fF. Color legend applies to A and B. B, interval between start of dialysis of GTPγS and Ca²⁺ and beginning of the exocytic burst. Line, mean; box, 25th–75th percentile; whiskers, 5th–95th percentile; n = number inside boxes. C, representative C_m traces at ∼10% of total ΔC_m. Signals <0 fF have been removed for clarity. Color legend applies to C and D. D, histogram of C_m step sizes between 1 and 15% of total ΔC_m. Signals <4 fF have been removed for clarity. n = numbers in B; ∼68 steps/cell. # = p < 0.05, † = p < 0.01, and * = p < 0.001; all comparisons are to Munc13-4^+/+ unless otherwise indicated.