title: Structure and dynamics of the fusion pore in live cells.
abstract: Atomic force microscopy reveal pit-like structures typically containing three or four, approximately 150 nm 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.
authors.affiliation: Department of Physiology and Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
authors.forename: Sang-Joon
authors.initials: SJ
authors.lastname: Cho
authors.forename: Anthony S
authors.initials: AS
authors.lastname: Quinn
authors.forename: Marvin H
authors.initials: MH
authors.lastname: Stromer
authors.forename: Sudhansu
authors.initials: S
authors.lastname: Dash
authors.forename: Jinah
authors.initials: J
authors.lastname: Cho
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Taatjes
authors.forename: Bhanu P
authors.initials: BP
authors.lastname: Jena
mesh_terms: D000681:Amylases / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure*; D003571:Cytochalasin B / Q000494:pharmacology; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D008561:Membrane Fusion; D018625:Microscopy, Atomic Force; D008954:Models, Biological; D010179:Pancreas / Q000166:cytology* / Q000648:ultrastructure*; D010455:Peptides; D051381:Rats; D017207:Rats, Sprague-Dawley; D014862:Wasp Venoms / Q000494:pharmacology
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D014862:Wasp Venoms; D003571:Cytochalasin B; C037500:mastoparan; D000681:Amylases