Robust polarity establishment involves the generation of a specific endocytic signature. (A) Kymograph of a polarizing WT cell expressing GFP-Sec4 and Abp1-RFP markers (left). Endocytic dynamics evolve from a series of discrete random events (left) to a pattern, or signature, of constant frequency and amplitude as the cell becomes stably polarized (right). The temporal change in intensity of the whole cell (black) was negligible compared with endocytic pattern at the cell cortex (red). (B) The temporal change in the intensity of random endocytic events of a nonpolarized cell (gray) versus regular events of constant amplitude in a polarized cell (red). (C) A scatter dot plot of the in silico (left) and in vivo (right) data comparing the frequency of endocytic events above the threshold (M&M) in nonpolarized (gray) versus polarized (red) cells. The black bars indicate the mean and SD over N events.