Cargo and Dynamin Regulate Clathrin-Coated Pit Maturation
Figure 1
Automated Tracking and Statistical Analyses Detect Three Subpopulations of CCPs at the Plasma Membrane
(A) A single frame from a 10-min video of BSC1 cells stably expressing EGFP-labeled clathrin LCa-EGFP (the scale bar indicates 2 μm).
(B) Overlay of all trajectories observed during the video.
(C) Lifetime distribution for CCPs determined in fast- (grey) and slow-acquisition (black) TIR-FM time-lapse videos. The distribution was determined from the elapsed time between the appearance and disappearance of fluorescent structures present in the time series. n = 43,568 CCP trajectories from 23 cells.
(D) Identification of three subpopulations of CCPs. Black dots and smoothed black line show distribution of all CCP lifetimes detected by TIR-FM. These data were best fit by three kinetically distinct subpopulations termed early abortive (blue line), late abortive (red line), and productive CCPs (green line).
(E and F) Relative contributions and lifetimes of subpopulations. Error bars represent cell-to-cell variation; the height of the lifetime bar in (F) denotes the t50-spread of the distribution, i.e., the range around the characteristic lifetime that contains 50% of the data.
Insets in (C, D, and F) show the data at different scales to emphasize short-lived CCP populations.