µ-conotoxin  SxIIIC (SxIIIC) is a 22 amino acid peptidyl toxin originally isolated from the venom of the cone snail, Conus striolatus¹. SxIIIC  is a potent and irreversible blocker of voltage-gated sodium (Na_v) channels, which displays a unique µ-conotoxin selectivity profile of human  (h)Na_V1.4 > hNa_V1.3 > hNa_V1.1 ≈ hNa_V1.6 ≈ hNa_V1.7 > hNa_V1.2 >> hNa_V1.5 ≈ hNa_V1.8¹.

Voltage-gated sodium channels (VGSCs) are transmembrane proteins that control the voltage-dependent increase in sodium permeability. VGSCs play a fundamental role in normal neurological function, especially in the initiation and propagation of action potentials. Na_v channels have been the topic of significant research and discussion for a considerable amount of time given their unique functions in electrical cell signaling. These channels are very important for homeostasis, thus specific genetic abnormalities in VGSC genes can result in a range of muscle, cardiac, and neurological disorders known as “channelopathies”². Marine toxins appear to be an emerging source of therapeutic tools that can relieve pain or treat VGSC-related human channelopathies³.