ABSTRACT
Electron micrographs (EM) morphometry of intracellularly located Zymogen Granules (ZG) in pancreatic acinar cells demonstrate that although the total number of ZG in cells remains unchanged following secretion, there is an increase in the number of empty and partially empty vesicles following a secretory episode, suggesting a transient kiss-and-run mechanism of intravesicular content release during cell secretion. Further confirmation of the transient kiss-and-run mechanism of cell secretion is demonstrated by the direct observation using atomic force microscopy (AFM) docked ZG at the apical plasma membrane in live pancreatic acinar cells. The supramolecular structure at the cell plasma membrane called 'porosome' that enables the kiss-and-run mechanism of secretion in cells was discovered in the mid 1990's and initially misnamed 'fusion pore'. In 2004, the neuronal porosome complex was discovered, isolated, and functionally reconstituted into artificial lipid membrane. Mass spectrometry (MS) of purified neuronal porosome complex, reveals the presence of approximately 40 proteins within the complex.
