Expression of SNAP-23 in SNAP-25 KO neurons leads to asynchronous release, which is exacerbated by deletion of Synaptotagmin-7.

<p>A, top: Representative EPSC traces of SNAP-25 KO neurons rescued with SNAP-25 (black) or SNAP-23 (blue) and SNAP-25/Syt-7 DKO neurons rescued with SNAP-25 (red), or SNAP-23 (green). Stimulation is indicated by an arrow. A, bottom: Representative mEPSC traces of SNAP-25 KO neurons rescued with SNAP-25 (black) or SNAP-23 (blue) and SNAP-25/Syt-7 DKO neurons rescued with SNAP-25 (red), or SNAP-23 (green). B: Expression of SNAP-23 in SNAP-25 KO neurons (blue) led to reduced peak EPSC amplitudes in SNAP-25 KO neurons, which were further significantly reduced in the absence of Syt-7 (green). In contrast, syt-7 deletion (red: SNAP-25 expression in SNAP-25/Syt-7 DKO neuron) was without consequence in the presence of SNAP-25 (black: SNAP-25 expression in SNAP-25 KO neuron). C: SNAP-23 rescued neurons displayed a 3–4 fold reduction in the charge transferred upon a stimulus; this reduction was independent of Syt-7 expression. D: The time-to-peak (EPSC) was prolonged in SNAP-23-rescued SNAP-25 KO neurons. Additional deletion of Syt-7 leads to a total of 50-fold increase in the time-to-peak. E: Spontaneous mEPSC amplitudes were unchanged in all four conditions. F: The frequency of mEPSCs was increased when SNAP-23 was expressed in SNAP-25 KO neurons, and further significantly increased when SNAP-23 was expressed in the SNAP-25/Syt-7 double KO background. G: Explanation of abbreviated labeling, used in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114033#pone-0114033-g002" target="_blank">Fig. 2</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114033#pone-0114033-g005" target="_blank">5</a>. * = p<0.05; ** = p<0.01; *** = p<0.001.</p>