To examine the freeze-fracture appearance of membrane alterations at sites of exocytosis in mammalian cells, we studied the secretory granule and plasma membrane of rat pancreatic B-cells during glucose-stimulated insulin secretion. Constant features observed were the scarcity of particles in secretory-granule P-fracture faces and the almost total clearance of intramembranous particles in P-and E fracture faces of the plasma membrane in areas of close apposition of these two membranes preceding fusion; also observed was the temporary persistence of particle-cleared regions after the fusion was completed. Our observations thus support the concept that membranes fuse at sites of closely apposed, particle-free regions and that the physiologically created clear areas found in freeze-fracture replicas of the plasma membrane are the hallmarks of incipient or recent membrane fusion.
Article| October 01 1977
Freeze-fracture of membrane fusions during exocytosis in pancreatic B-cells.
D S Friend
Online Issn: 1540-8140
Print Issn: 0021-9525
J Cell Biol (1977) 75 (1): 23–30.
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L Orci, A Perrelet, D S Friend; Freeze-fracture of membrane fusions during exocytosis in pancreatic B-cells.. J Cell Biol 1 October 1977; 75 (1): 23–30. doi: https://doi.org/10.1083/jcb.75.1.23
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