(A) Average SNX9 intensity trace for CCPs found to nucleate in hotspots (red) is compared to the average SNX9 intensity trace of CCPs found to nucleate outside hotspots (blue), and to the average clathrin intensity trace of all CCPs (black). 678 CCPs (430 hotspot CCPs, 345 outside nucleated CCPs) with a lifetime 60 – 80 s from 7 cells were used. SNX9 intensities were normalized to the maximal average SNX9 intensity of CCPs in hotspots; clathrin intensities were normalized to the maximal average clathrin intensity of the combined population of CCPs inside and outside hotspots. (B) Mean intensity (normalized by same factor as SNX9 traces in A) from 30 s to 6 s before CCP nucleation, and from 6 s to 30 s after CCP internalization for all CCPs (8 – 100 s in lifetime) found to nucleate in hotspots (hotspots), for CCPs that nucleate and remain in hotspots (remain in hotspots), for CCPs that nucleate in and then diffuse away from a hotspot (leave hotspots), and for CCPs that nucleate outside hotspots (random); n = 3797, 2003, 1794, and 3146 CCPs respectively. Error bars represent the standard error of the mean. (C) Average FCHo2 and clathrin intensities for CCPs with a lifetime 60 – 80 s (2606 hotspot CCPs, 1682 outside nucleated CCPs from 6 cells were used). (D) Average AP-2 (σ2-EGFP) and clathrin intensities for CCPs with a lifetime 60 – 80 s (1038 hotspot CCPs, 483 outside nucleated CCPs from 8 cells were used). AP-2 and FCHo2 intensity traces were normalized in the same manner as SNX9. SNX9, AP-2, and FCHo2 intensity traces in the background were obtained by sampling random partner intensity traces for each CCP at a distance of 134 nm.