STRUCTURE AND DYNAMICS OF THE FUSION PORE IN LIVE CELLS

• DOI: 10.1006/cbir.2001.0849
• Publication Date: 2002-10-06T19:02:41Z
• Authors: Sang‐Joon Cho; Anthony S. Quinn; Marvin H. Stromer; Sudhansu Dash; Jinah Cho; Douglas J. Taatjes; Bhanu P. Jena
• Keywords: Male; 0301 basic medicine; 0303 health sciences; Cytochalasin B; Blotting, Western; Cell Membrane; Wasp Venoms; Microscopy, Atomic Force; Immunohistochemistry; Membrane Fusion; Models, Biological; Rats; Rats, Sprague-Dawley; 03 medical and health sciences; Amylases; Animals; Intercellular Signaling Peptides and Proteins; Peptides; Pancreas

Atomic force microscopy reveal pit‐like structures typically containing three or four, ∼150nm in diameter depressions at the apical plasma membrane in live pancreatic acinar cells. Stimulation of secretion causes these depressions to dilate and return to their resting size following completion of the process. Exposure of acinar cells to cytochalasin B results in decreased depression size and a loss in stimulable secretion. It is hypothesized that depressions are the fusion pores, where membrane‐bound secretory vesicles dock and fuse to release vesicular contents. Zymogen granules, the membrane‐bound secretory vesicles in exocrine pancreas, contain the starch digesting enzyme, amylase. Using amylase‐specific immunogold labeling, localization of amylase at depressions following stimulation of secretion is demonstrated. This study confirms depressions to be the fusion pores in pancreatic acinar cells. High‐resolution images of the fusion pore in live pancreatic acinar cells reveal the structure in much greater detail than has previously been observed.