Regulation of the priming of exocytosis and the dissociation of SNAP-25 and VAMP-2 in adrenal chromaffin cells.
The MgATP-dependent priming step of exocytosis has been suggested to be regulated negatively by GTP-binding protein G0 in permeabilized adrenal chromaffin cells. We have reported that synaptosomal-associated protein of 25 kDa (SNAP-25) and vesicle-associated membrane protein 2 (VAMP-2) form a complex in chromaffin cells, and the complex dissociates during MgATP-dependent priming. In this study, we examined whether G0 controls such dissociation of the SNAP-25/VAMP-2 complex in the regulation of priming. In digitonin-permeabilized cells, MgATP-gamma-S which can be a phosphate donor for protein phosphorylation failed to cause priming and dissociation of the SNAP-25/VAMP-2 complex. Mastoparan, which directly activates G0, selectively inhibited priming and blocked dissociation of the SNAP-25/VAMP-2 complex. These results suggest that ATP hydrolysis and dissociation of the SNAP-25/VAMP-2 complex are responsible for priming. These results also suggest that dissociation of the complex is one of the sequential steps for priming controlled by G0.
Misonou
H
H
Life Science Institute, Sophia University, Tokyo, Japan.
Ohara-Imaizumi
M
M
Kumakura
K
K
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000311:Adrenal Glands / Q000187:drug effects*; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured / Q000187:drug effects; D019439:Chromaffin Cells / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005033:Ethylmaleimide / Q000494:pharmacology; D005089:Exocytosis / Q000187:drug effects*; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000187:drug effects*; D009419:Nerve Tissue Proteins / Q000187:drug effects*; D010455:Peptides; D050683:R-SNARE Proteins; D050825:Synaptosomal-Associated Protein 25; D014862:Wasp Venoms / Q000494:pharmacology
D004791:Enzyme Inhibitors; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D010455:Peptides; D050683:R-SNARE Proteins; D050825:Synaptosomal-Associated Protein 25; D014862:Wasp Venoms; C037500:mastoparan; D000255:Adenosine Triphosphate; D005033:Ethylmaleimide