Micromolar concentrations of PiVIIA increase the magnitude of the macroscopic calcium current in DRG neurons from rat. An increase, even modest of the calcium current, may have a significant impact in the excitability and electrical activity of neurons, and may set up PiVIIA as a member of the pharmacological family of the gamma-conotoxins. Expressed by the venom duct. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. The cysteine framework is VI/VII (C-C-CC-C-C). Monoisotopic mass. Does not modify sodium, potassium and acid sensing ionic channel (ASIC) currents. Belongs to the conotoxin O2 superfamily.