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In Vitro Analysis of PDZ-dependent CFTR Macromolecular Signaling Complexes
Published on: August 13, 2012
Cysteine string protein regulates G protein modulation of N-type calcium channels
J M Magga1, S E Jarvis, M I Arnot
1Department of Physiology and Biophysics, University of Calgary, Alberta, Canada.
Abstract:
Cysteine string proteins (CSPs) are secretory vesicle proteins bearing a "J domain" and a palmitoylated cysteine-rich "string" region that are critical for neurotransmitter release. The precise role of CSP in neurotransmission is controversial. Here, we demonstrate a novel interaction between CSP, receptor-coupled trimeric GTP binding proteins (G proteins), and N-type Ca2+ channels. G. subunits interact with the J domain of CSP in an ATP-dependent manner; in contrast, Gbetagamma subunits interact with the C terminus of CSP in both the presence and absence of ATP. The interaction of CSP with both G proteins and N-type Ca2+ channels results in a tonic G protein inhibition of the channels. In view of the crucial importance of N-type Ca2+ channels in presynaptic vesicle release, our data attribute a key role to CSP in the fine tuning of neurotransmission.
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