Endocytic cortical corralling is required for robust polarity establishment. The endo- and exocytic vesicles are marked by Abp1-RFP (red) and GFP-Sec4 (cyan), respectively. (A, top) The kymograph of an in silico sla2Δ mutant cell shows depolarized endocytic events throughout the simulation, whereas exocytic clusters were unstable in the absence of corralling. (bottom) In vivo analysis shows polarizing sla2Δ cells to exhibit single or multiple exocytic poles with randomly distributed endocytic sites. Bars, 2 µm. (B) Abp1-RFP (closed circle) and GFP-Rvs167 (open circle) residency times in actin patches for WT (red) and sla2Δ (purple) cells, represented by a scatter dot plot. The black lines indicate the mean and SD over N patches. Mean residency times of the proteins were significantly different between WT and sla2Δ cells (P < 0.0001). (C) The temporal change in the intensity of endocytic events reveals a random endocytic pattern for polarized sla2Δ cells (purple) in contrast to polarized WT cells (red). (D) A scatter dot plot depicting the frequency of endocytic events above the threshold in polarized endocytic mutants such as sla2Δ (purple), sla1Δ bbc1Δ (blue), and rvs167Δ rvs161Δ (pink) versus polarized WT cells (red). The black bars indicate the mean and SD over N events.