Mu-conotoxins block voltage-gated sodium channels (Nav). This toxin moderately blocks rNav1.1/SCN1A, rNav1.2/SCN2A, rNav1.3/SCN3A, rNav1.4/SCN4A, and mNav1.6/SCN8A. 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. Does not inhibit Nav1.5/SCN5A (PubMed:18522941), Nav1.7/SCN9A (PubMed:18522941) and Nav1.8/SCN10A (PubMed:18522941, PubMed:21652776). Belongs to the conotoxin M superfamily. All results of mutagenesis experiments are compared with the mutant DEL-52.