Enhancement of presynaptic calcium current by cysteine string protein.
The isolated chick ciliary neuron calyx synapse preparation was used to test cysteine string protein (CSP) action on presynaptic N-type Ca(2+) channels. Endogenous CSP was localized primarily to secretory vesicle clusters in the presynaptic nerve terminal. Introduction of recombinant CSP into the voltage clamped terminal resulted in a prominent increase in Ca(2+) current amplitude. However, this increase could not be attributed to a change in Ca(2+) channel kinetics, voltage dependence, prepulse inactivation, or G protein inhibition but was attributed to the recruitment of dormant channels. Secretory vesicle associated endogenous CSP may play an important role in enhancing Ca(2+) channel activity at the transmitter release site.
Chen
Shan
S
Synaptic Mechanisms Section, NINDS, NIH, Bethesda, MD 20892-4156, USA.
Zheng
Xu
X
Schulze
Karen L
KL
Morris
Terry
T
Bellen
Hugo
H
Stanley
Elis F
EF
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002642:Chick Embryo; D004553:Electric Conductivity; D050956:HSP40 Heat-Shock Proteins; D066298:In Vitro Techniques; D008565:Membrane Proteins / Q000494:pharmacology / Q000502:physiology*; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D014018:Tissue Distribution
D015220:Calcium Channels; D050956:HSP40 Heat-Shock Proteins; D008565:Membrane Proteins; D011994:Recombinant Proteins; C088460:cysteine string protein