Differential regulation of exocytosis by calcium and CAPS in semi-intact synaptosomes.
Using a novel approach to measure exocytosis in vitro from semi-intact synaptosomes, we establish that the Ca2+-dependent release of glutamate requires cytosolic factors for mobilization from the reserve pool. The cytosolic activity for glutamate release was not satisfied by CAPS, a soluble component required for norepinephrine (NE) release. Moreover, the CAPS-independent glutamate release from synaptic vesicles (SVs) was 200-fold less sensitive to Ca2+ than that required for dense core vesicles (DCVs). The differential regulation of exocytosis by CAPS, Ca2+, and potential novel cytosolic factor(s) suggests that the docking and fusion machinery controlling DCVs has diverged from that regulating glutamate-containing SVs.
Tandon
A
A
Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
Bannykh
S
S
Kowalchyk
J A
JA
Banerjee
A
A
Martin
T F
TF
Balch
W E
WE
D000818:Animals; D029742:Caenorhabditis elegans Proteins; D002118:Calcium / Q000502:physiology*; D002135:Calcium-Binding Proteins; D003600:Cytosol / Q000378:metabolism / Q000502:physiology; D005089:Exocytosis / Q000502:physiology*; D018698:Glutamic Acid / Q000378:metabolism; D015801:Helminth Proteins / Q000276:immunology / Q000502:physiology*; D008297:Male; D008565:Membrane Proteins / Q000502:physiology; D018377:Neurotransmitter Agents / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D050600:SNARE Proteins; D013574:Synaptosomes / Q000378:metabolism / Q000502:physiology*; D033921:Vesicular Transport Proteins
D029742:Caenorhabditis elegans Proteins; D002135:Calcium-Binding Proteins; D015801:Helminth Proteins; D008565:Membrane Proteins; D018377:Neurotransmitter Agents; D050600:SNARE Proteins; C107581:UNC-31 protein, C elegans; D033921:Vesicular Transport Proteins; D018698:Glutamic Acid; D002118:Calcium