Large dense-core vesicle exocytosis in PC12 cells.

A current major challenge in the study of regulated exocytosis is the identification of essential proteins that mediate the transit of secretory vesicles through trafficking stages such as recruitment, docking, and fusion. Defining the physiological roles and mechanisms of action of these essential proteins is paramount. The reconstitution of stages of regulated exocytosis in cell-free systems provides the opportunity to identify required proteins and establish their stage-specific mechanisms of action. PC12 cells, clonal cell lines of adrenal medullary origin, possess large dense-core vesicles that retain their competence for regulated exocytosis in a variety of permeable cell and isolated membrane preparations. We describe several cell-free systems for studies of regulated exocytosis derived from PC12 cells.