A specific interaction in vitro between pancreatic zymogen granules and plasma membranes: stimulation by G-protein activators but not by Ca2+.
The molecular details of the final step in the process of regulated exocytosis, the fusion of the membrane of the secretory granule with the plasma membrane, are at present obscure. As a first step in an investigation of this membrane fusion event, we have developed a cell-free assay for the interaction between pancreatic zymogen granules and plasma membranes. We show here that plasma membranes are able to trigger the release of the granule contents, and that this effect is specific to pancreatic membranes, involves membrane fusion, requires membrane proteins, and is stimulated by activators of G-proteins but not by Ca2+. The assay is simple, reliable, and rapid, and should permit the identification of proteins that are involved in the exocytotic fusion event.
Nadin
C Y
CY
Department of Pharmacology, University of Cambridge, United Kingdom.
Rogers
J
J
Tomlinson
S
S
Edwardson
J M
JM
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D003594:Cytoplasmic Granules / Q000201:enzymology* / Q000648:ultrastructure; D004792:Enzyme Precursors / Q000378:metabolism*; D005089:Exocytosis / Q000187:drug effects; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D007700:Kinetics; D008099:Liver / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D008561:Membrane Fusion; D008565:Membrane Proteins / Q000378:metabolism; D010179:Pancreas / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D013873:Thionucleotides / Q000494:pharmacology; D000516:alpha-Amylases / Q000378:metabolism
D004792:Enzyme Precursors; D008565:Membrane Proteins; D013873:Thionucleotides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D000516:alpha-Amylases; D019204:GTP-Binding Proteins; D002118:Calcium