Mu-conotoxins block voltage-gated sodium channels (Nav). This synthetic toxin blocks both voltage-gated sodium channels and nicotinic acetylcholine receptor (nAChR). Inhibits the skeletal muscle rNav1.4/SCN4A (IC(50)=1.3 nM) and the brain rNav1.2/SCN2A in a long-lasting manner. A low inhibition is also observed on neuronal mNav1.6/SCN8A and mNav1.7/SCN9A. Modestly blocks nAChR alpha-3/beta-2 subtype (IC(50)=450 nM) (partially reversible) and, to a lesser extent, alpha-7 and alpha-4/beta-2 subtypes (reversible). In vitro, decreases twitch tension in mouse hemidiaphragms (IC(50)=150 nM), and displays a high blocking effect in mouse extensor digitorum longus muscles (IC(50)=46 nM). Expressed by the venom duct. The cysteine framework is III (CC-C-C-CC). Classified in the M-5 branch, since 5 residues stand between the fourth and the fifth cysteine residues. CnIIIC, monoisotopic. CnIIIC. [Gln1]-CnIIIC. Is commercialized under the name XEP-018 by Activen in the cosmetic area. When applied as a cream, it is claimed to reduce fine-line wrinkles. 1 uM does not block cardiac mNav1.5/SCN5A and DRG-specific rNav1.8/SCN10A channels. 5 uM does not block voltage-gated potassium channels rKv1.1/KCNA1, rKv1.2/KCNA2, hKv1.3/KCNA3, rKv1.4/KCNA4, rKv1.5/KCNA5, rKv1.6/KCNA6, Shaker, hERG1/KCNH2 (PubMed:22229737). Found in both injectable (milked) (IV) and dissected venom (DV) (PubMed:22705119 and PubMed:22229737). Belongs to the conotoxin M superfamily.