This toxin significantly slows the fast inactivation of Nav1.2/SCN2A (EC(50)=580 nM), Nav1.3/SCN3A (EC(50)=1310 nM), Nav1.4/SCN4A (EC(50)=530 nM), and Nav1.7/SCN9A (EC(50)=1340 nM). The toxin does not affect the peak amplitude of Nav1.7 currents. On all channels cited above, the toxin requires depolarizing potentials to slow channel inactivation. In addition, the toxin has no or very weak effects on the voltage-dependence of steady-state inactivation, and on voltage-dependence of activation. In vivo, it produces paw licking in mice equivalent to the effects of whole venom. Expressed by the venom gland. Has the structural arrangement of an alpha-helix connected to antiparallel beta-sheets by disulfide bonds (CS-alpha/beta). Has a minimal effect on Nav1.5/SCN5A and no effect on Nav1.8/SCN10A and Nav1.9/SCN11A sodium channels. Belongs to the long (4 C-C) scorpion toxin superfamily. Sodium channel inhibitor family. Extended N-terminus.