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Updated: Oct 10, 2026

A Kinetic Fluorescence-based Ca2+ Mobilization Assay to Identify G Protein-coupled Receptor Agonists, Antagonists, and Allosteric Modulators
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A Kinetic Fluorescence-based Ca2+ Mobilization Assay to Identify G Protein-coupled Receptor Agonists, Antagonists, and Allosteric Modulators

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Cross-talk between G-protein and protein kinase C modulation of N-type calcium channels is dependent on the G-protein

C B Cooper1, M I Arnot, Z P Feng

  • 1Departments of Physiology & Biophysics and Pharmacology & Therapeutics, Neuroscience and Smooth Muscle Research Groups, University of Calgary, Calgary, Alberta T2N 4N1, Canada.

The Journal of Biological Chemistry
|October 29, 2000
PubMed

Insights

Protein kinase C (PKC) and G-protein cross-talk selectively involves the Gbeta(1) subunit in modulating N-type calcium channels. This interaction fine-tunes neurotransmitter release, with specific G-protein beta subunits influencing channel activity.

Area of Science:

  • Neuroscience
  • Molecular Biology
  • Pharmacology

Background:

  • N-type calcium channels are crucial for neurotransmitter release, modulated by protein kinases and G-proteins.
  • Previous work identified the alpha(1B) calcium channel I-II linker as a cross-talk integration center for protein kinase C (PKC) and G-proteins.
  • Somatostatin receptor-mediated inhibition is significantly reduced by T422 phosphorylation, indicating PKC/G-protein interaction.

Purpose of the Study:

  • To investigate if PKC/G-protein cross-talk in N-type calcium channel modulation is dependent on the specific G-protein beta subunit involved.
  • To elucidate the role of different G-protein beta subunits (Gbeta1-4) in the interaction between PKC and G-proteins at the alpha(1B) calcium channel.

Main Methods:

  • Utilized mutant alpha(1B) calcium channels with T422 residue replaced by glutamate to mimic PKC phosphorylation.
  • Examined channels directly phosphorylated by PKC.
  • Assessed the effects of four distinct G-protein beta subunits (Gbeta1-4) on wild-type and mutant channels.

Main Results:

  • Phosphorylation or mutation at residue 422 antagonized the inhibitory effect of the Gbeta(1) subunit on channel activity.
  • Gbeta(2), Gbeta(3), and Gbeta(4) subunits did not show significant interaction or modulation with the phosphorylated/mutant channel.
  • Opioid receptor-mediated inhibition was less affected than somatostatin receptor-mediated inhibition, suggesting subtype specificity.

Conclusions:

  • The cross-talk between G-proteins and PKC in modulating N-type calcium channels is a selective process involving the Gbeta(1) subunit.
  • This selectivity is critical for the fine-tuning of neurotransmitter release.
  • The findings highlight the subunit-specific nature of G-protein signaling in neuronal function.

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