New Structure Involved in Transient Membrane Fusion and Exocytosis

Abstract

Our studies using atomic force microscopy (AFM) reveal a new group of plasma membrane structures involved in exocytosis in live pancreatic acinar cells. These studies demonstrate that "pits" and "depressions" are sites at the apical plasma membrane in live cells, where membrane-bound secretory vesicles dock and transiently fuse to release vesicular contents.

The sory of cell secretion: events leading to the dicovery of the ‘porosome’- the universal secretory machinery in cells

“…High resolution AFM examination of live GH cells [34], chromaffin cells [35], β-cells [36], mast cells [36], and neurons [37] demonstrated the presence of porosomes [36]. Similar to pancreatic acinar cells, porosomes in GH cells, when stimulated by a secretagogue, results in a 40% increase in diameter, which is cytocholasin-sensitive, demonstrating the involvement of actin in its morphology and function [34].…”

Cell Seretion-finally sees the light

“…The critical breakthrough came with the discovery of the 'porosome', the universal secretory machinery at the cell plasma membrane, where membrane-bound secretory vesicles dock and transiently fuse to expel intravesicular contents to the outside [1][2][3][4][5][6][7]. What took so long for this discovery?…”

Direct interaction between SNAP-23 and L-type Ca2+channel

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Atomic force microscopy (AFM) in combination with electron microscopy (EM) and biochemical approaches, has helped in the discovery of the fusion pore or porosome at the cell plasma membrane, where secretory vesicles dock and fuse to release their contents [1][2][3][4][5][6][7]. The structure of the porosome in both exocrine [1,2,5,6], neuroendocrine cells [3,4], and in neurons [7], at nanometer-subnanometer resolution, and its dynamics in real time, have been determined.

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“…The structure of the porosome in both exocrine [1,2,5,6], neuroendocrine cells [3,4], and in neurons [7], at nanometer-subnanometer resolution, and its dynamics in real time, have been determined. Immunochemical studies further demonstrate that t-SNAREs, NSF, actin, vimentin, α-fodrin and the calcium channels α1c and β 3, are part of the fusion pore complex [5,6].…”