Figure 3.

Effects of Ca²⁺-binding mutations in each Syt1 C2 domain on evoked synchronous release. A, Representative traces of two consecutive eEJP responses are shown for wild-type, syt1^−/− (null), and syt1^−/− rescued with the indicated transgenic constructs. Example traces are shown for recordings at low (0.2 mm, top) and high (1.0 mm, bottom) [Ca²⁺] in HL3.1 saline. Calibration: 5 mV, 200 ms. B, The mean amplitude of EJP responses are summarized for each genotype indicated. C, Failure rates, calculated by counting trials with no detectable eEJP for 40 consecutive stimuli, are shown for each genotype. B, C, Data are mean ± SEM. ***p < 0.001, **p < 0.01, and *p < 0.05, one-way ANOVA with multiple comparisons using the Fisher's LSD test between syt1^−/− rescued with the C2A-C2B and the indicated genotypes. Number of NMJs examined (0.2 and 1.0 mm [Ca²⁺]_o): WT, 7 and 7; syt^−/−, 6 and 16; syt^−/−, C2A-C2B, 10 and 11; syt^−/−, C2A*-C2B, 9 and 7; syt^−/−, C2A-C2B*, 6 and 10; and syt^−/−, C2A*-C2B*, 6 and 12.