Figure 1.

Simulation of membrane capacitance decay at a fusion site due to clathrin-dependent endocytosis or both clathrin-dependent and -independent endocytosis. INS-1 cells were transfected with VAMP2-pHluorin and clathrin-DsRed and were stimulated with 70 mM KCl and 15 mM glucose. Overall, 55 ± 3% of vesicle fusion events were associated with on-site recruitment of dynamin 1. (A) Normalized histogram of departure times of recruited Dyn1 puncta at fusion sites. It can be fitted with a three-component Gaussian distribution centered at 2.3 ± 0.11, 10.4 ± 0.5, and 23.3 ± 3.7 s and contributing to ~39 ± 3, 24 ± 6, and 34 ± 8% of the total population, respectively (n = 246). The latter two populations were dependent on clathrin, while the first one was independent of clathrin (Figure S2 in He et al., 2009). (B) Normalized histogram of departure times of recruited Clathrin puncta at fusion sites. It can be fitted with a two-component Gaussian distribution centered at 6.9 ± 0.5 and 28.9 ± 2.6 s and contributing to ~50 ± 4 and 44 ± 6% of the total population, respectively (n = 215). (C) A scheme of how clathrin-dependent and independent endocytosis are differently coupled to exocytosis.