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Updated: Aug 9, 2026
Identification of Specific Sensory Neuron Populations for Study of Expressed Ion Channels
Published on: December 24, 2013
Novel omega-conotoxins from Conus catus discriminate among neuronal calcium channel subtypes
R J Lewis1, K J Nielsen, D J Craik
1Centre for Drug Design and Development (3D Centre), Institute for Molecular Bioscience, Department of Physiology and Pharmacology, CSIRO Tropical Agriculture, and Queensland Agricultural Biotechnology Centre (QDPI), Australia. r.lewis@mailbox.uq.edu.au
Abstract:
omega-Conotoxins selective for N-type calcium channels are useful in the management of severe pain. In an attempt to expand the therapeutic potential of this class, four new omega-conotoxins (CVIA-D) have been discovered in the venom of the piscivorous cone snail, Conus catus, using assay-guided fractionation and gene cloning. Compared with other omega-conotoxins, CVID has a novel loop 4 sequence and the highest selectivity for N-type over P/Q-type calcium channels in radioligand binding assays. CVIA-D also inhibited contractions of electrically stimulated rat vas deferens. In electrophysiological studies, omega-conotoxins CVID and MVIIA had similar potencies to inhibit current through central (alpha(1B-d)) and peripheral (alpha(1B-b)) splice variants of the rat N-type calcium channels when coexpressed with rat beta(3) in Xenopus oocytes. However, the potency of CVID and MVIIA increased when alpha(1B-d) and alpha(1B-b) were expressed in the absence of rat beta(3), an effect most pronounced for CVID at alpha(1B-d) (up to 540-fold) and least pronounced for MVIIA at alpha(1B-d) (3-fold). The novel selectivity of CVID may have therapeutic implications. (1)H NMR studies reveal that CVID possesses a combination of unique structural features, including two hydrogen bonds that stabilize loop 2 and place loop 2 proximal to loop 4, creating a globular surface that is rigid and well defined.
Insights
Four novel omega-conotoxins were discovered, with CVID showing high selectivity for N-type calcium channels. This discovery may lead to new pain management therapies by targeting specific channel variants.
Area of Science:
- Marine Biology
- Neuropharmacology
- Biochemistry
Background:
- Omega-conotoxins targeting N-type calcium channels are valuable for severe pain management.
- The venom of Conus catus is a source of novel conotoxins with therapeutic potential.
Purpose of the Study:
- To discover and characterize new omega-conotoxins from Conus catus venom.
- To evaluate the selectivity and potency of novel conotoxins, particularly CVID, for N-type calcium channels.
Main Methods:
- Assay-guided fractionation and gene cloning were used to isolate new conotoxins.
- Radioligand binding assays and electrophysiological studies (Xenopus oocytes) assessed channel selectivity and inhibition.
- 1H NMR spectroscopy was employed to determine the structural features of CVID.
Main Results:
- Four new omega-conotoxins (CVIA-D) were identified from Conus catus venom.
- CVID exhibited high selectivity for N-type over P/Q-type calcium channels and inhibited rat vas deferens contractions.
- CVID and MVIIA potency increased significantly in the absence of beta(3) subunits, especially CVID at the alpha(1B-d) splice variant.
Conclusions:
- The novel omega-conotoxin CVID possesses unique structural features and high selectivity for N-type calcium channels.
- The differential effects of beta(3) subunits on CVID and MVIIA potency highlight specific interactions with N-type calcium channel variants.
- The distinct properties of CVID suggest potential for developing targeted pain therapeutics.
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