Dissociation of SNAP-25 and VAMP-2 by MgATP in permeabilized adrenal chromaffin cells.
In digitonin-permeabilized adrenal chromaffin cells, Ca(2+)-induced catecholamine release can be resolved into at least two sequential steps: a MgATP-dependent priming step and a MgATP-independent Ca(2+)-triggered step. Botulinum neurotoxins types A and E cleaved SNAP-25, and blocked MgATP-independent Ca(2+)-induced catecholamine release from the permeabilized chromaffin cells. When the permeabilized cells were primed by pretreatment with MgATP, the amount of SNAP-25 associated with VAMP-2 decreased, and the fraction of SNAP-25 proteolyzed by the neurotoxins increased. These results suggest that dissociation of SNAP-25 and VAMP-2 occurs during the MgATP-dependent priming step, and SNAP-25 plays some important roles in the subsequent MgATP-independent step.
Misonou
H
H
Life Science Institute, Sophia University, Tokyo, Japan.
Nishiki
T
T
Sekiguchi
M
M
Takahashi
M
M
Kamata
Y
Y
Kozaki
S
S
Ohara-Imaizumi
M
M
Kumakura
K
K
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism; D002417:Cattle; D002463:Cell Membrane Permeability; D019439:Chromaffin Cells / Q000737:chemistry / Q000378:metabolism*; D004072:Digitonin; D004591:Electrophoresis, Polyacrylamide Gel; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000302:isolation & purification / Q000378:metabolism*; D011233:Precipitin Tests; D050765:Qa-SNARE Proteins; D050683:R-SNARE Proteins; D050825:Synaptosomal-Associated Protein 25
D002395:Catecholamines; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D050765:Qa-SNARE Proteins; D050683:R-SNARE Proteins; D050825:Synaptosomal-Associated Protein 25; D000255:Adenosine Triphosphate; D004072:Digitonin; D002118:Calcium