Omega-conotoxins act at presynaptic membranes, they bind and block voltage-gated calcium channels (Cav). Reversibly blocks calcium current in the dorsal-root ganglion neurons of the rat (high voltage-activated channels but not low voltage-activated channels). Does not modify the voltage dependency of activation and inactivation. Expressed by the venom duct. The cysteine framework is XVI (C-C-CC). Contains 2 disulfide bonds.