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Synaptotagmin C2b Ca2+-Binding Loops Impose Distinct Exocytosis Phenotypes, Michael W. Schmidtke

Wayne State University Theses

Regulated exocytosis from chromaffin cells in the adrenal medulla plays a critical role in maintaining organismal homeostasis. In the absence of stress, these cells release physiologically relevant substances into the blood stream only in limited quantities, whereas stressful conditions result in a rapid deluge of signaling molecules used, for example, to increase heart rate and pain tolerance. Although the cellular mechanisms governing the switch from low-level to stress-induced secretion are not well understood, recent evidence has implicated the exocytotic Ca2+-sensing protein Synaptotagmin (Syt) in this role.

Two isoforms of Syt are expressed in chromaffin cells (Syt-1 and Syt-7), and each …