To determine whether VPS13C might conceivably affect the properties (i.e., “fusogenecity”), or the distribution of secretory granules, we explored the localization of the protein with single human β-cells by confocal immunocytochemistry (Fig. 12). Close colocalization was observed between insulin and VPS13C-labeled structures, indicative of the presence of the latter on the limiting membrane of insulin-containing dense core granules.