Neuron
Volume 14, Issue 1, January 1995, Pages 191-200
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Article
Transmitter-mediated inhibition of N-type calcium channels in sensory neurons involves multiple GTP-binding proteins and subunits

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Abstract

The modulation of voltage-activated Cat+ channels by neurotransmitters and peptides is very likely a primary means of regulating Ca 2+-dependent physiological functions such as neurosecretion, muscle contraction, and membrane excitability. In neurons, N-type Ca2+ channels (defined as ω-conotoxin GVIA-sensitive) are one prominent target for transmitter-mediated inhibition. This inhibition is widely thought to result from a shift in the voltage dependence of channel gating. Recently, however, voltage-independent inhibition has also been described for N channels. As embryonic chick dorsal root ganglion neurons express both of these biophysically distinct modulatory pathways, we have utilized these cells to test the hypothesis that the voltage-dependent and -independent actions of transmitters are mediated by separate biochemical pathways. We have confirmed this hypothesis by demonstrating that the two modulatory mechanisms activated by a single transmitter involve not only different classes of G protein but also different G protein subunits.

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