EXOCYTOSIS - PROTEINS AND PERTURBATIONS

Exocytosis is the primary means of cellular secretion. Because exocyto sis involves fusion between the plasma membrane and the membrane of se cretory vesicles, it is likely that proteins on these two membranes, a s well as additional proteins in cellular cytoplasm, mediate exocytosi s. Although we know much about the proteins of secretory cells, we sti ll have much to learn about how these proteins participate in exocytos is; in no case has an unambiguous exocytotic function been assigned to any of these proteins. To identify the roles of proteins in exocytosi s it is necessary to perturb protein function in living secretory cell s. We review a number of perturbation strategies and summarize what th is approach has taught us about the functional roles of proteins in ex ocytosis, concluding with a molecular model of protein dynamics during exocytosis.