Figure 1.

Schematic of the flickering dynamics of membrane fusion pores. A vesicle docks onto a planar membrane by complexation of vesicle v-SNAREs (blue on vesicle) with t-SNAREs (red, yellow, and green on SBL). Fusion of the membranes creates an open pore through which contents are released. Live-cell electrophysiological studies show that fusion pores may flicker rapidly and repeatedly between closed and open states, then dilate to become fully developed pores or permanently close. In this study, we track flickering of fusion pores by monitoring release of labeled vesicle membrane lipids (yellow) into the planar membrane (Fig. 2). Simultaneous observations of lipid and content release are also made (Fig. 3). Release is retarded because the pore is open only a fraction, $P_{\text{o}},$ of the time. To see this figure in color, go online.