EXOCYTOSIS IN EXCITABLE CELLS - A CONSERVED MOLECULAR MACHINERY FROM YEAST TO NEURON

One of the basic cellular functions of nearly every cell type is the e xocytotic release of synthesized molecules, stored and packaged into i ntracellular vesicles or granules. A variety of approaches has been us ed to identify and characterize the molecules that mediate vesicular t rafficking along the secretory pathway. The findings obtained with the se approaches suggest that common mechanisms may underlie a wide varie ty of vesicle-mediated transport steps. This review presents some of t he recent findings regarding the study of the cellular mechanisms whic h control neurotransmitter and hormone release from neurons and endocr ine cells respectively, and focuses on regulation of these mechanisms. The similarities between these two cell types can be seen as evidence to support the hypothesis according to which the regulated exocytosis apparatus could have evolved from a constitutive fusion machinery to which some key modulators have been added. Insight into secretory vesi cles will be relevant not only to the understanding of vesicular traff icking or cell polarity but also to the understanding of higher nervou s functions resulting from synaptic plasticity.