An early endosome–derived retrograde trafficking pathway promotes secretory granule maturation

Regulated secretion is a fundamental cellular process in which biologically active molecules stored in long-lasting secretory granules (SGs) are secreted in response to external stimuli. Many studies have described mechanisms responsible for biogenesis and secretion of SGs, but how SGs mature remains poorly understood. In a genetic screen, we discovered a large number of endolysosomal trafficking genes required for proper SG maturation,...