Biogenesis of constitutive secretory vesicles, secretory granules, and synaptic vesicles-£acts and concepts

Abstract Vesicle-mediated secretion from animal cells utilizes three types of secretory vesicles (1, 2) (Fig. 1). The first type is the constitutive secretory vesicle (CSV), which is thought to be common to all eukaryotic cells and which mediates the continuous secretion of newly synthesized proteins. The second type is the secretory granule, in neurones also referred to as the large dense core vesicle, which occurs only in cells capable of regulated protein secretion and which mediates the stimulus-dependent release of stored proteins and biogenic amines. The third type is the synaptic vesicle of neurones, which mediates the release of neurotransmitters but lacks secretory proteins, and its counterpart in certain endocrine cells, the synaptic-like microvesicle (SLMV). In this chapter, we will summarize current knowledge, and describe concepts concerning the molecular machinery involved in the biogenesis of these vesicles, its regulation, and the protein sorting processes that occur in the course of vesicle formation.