Figure 4.

Mechanism of blocking neuromuscular transmission. The “motor cabal” of toxins (see text) targets multiple components in the neuromuscular circuit (top panel). Three different toxins (ω-, α- and μ-conotoxins) act on three different target components: 1) presynaptic Ca²⁺ channels; 2) nicotinic acetylcholine receptors; and 3) voltage-gated skeletal muscle Na⁺ channels. Bottom panel, synergy in Conus venoms is achieved both by inhibiting multiple components as well as multiple sites in a single macromolecular component. Two unrelated toxins (α- and Ψ-conotoxins) inhibit one receptor, the postsynaptic nicotinic acetylcholine receptor at different sites.