Sigma-conotoxins bind and inhibit serotonin-gated ion channels. This peptide selectively and reversibly inhibits 5-hydroxytryptamine 3 receptor (HTR3A) through competitive antagonism (IC(50)=53-86.8 nM). Expressed by the venom duct. The cysteine framework is VIII (C-C-C-C-C-C-C-C-C-C). Contains 5 disulfide bonds. Monoisotopic mass. Belongs to the conotoxin S superfamily.