Blocks potassium channels Kv1.2/KCNA2 and Kv1.3/KCNA3 with high affinity (K(d)=1.9 nM and 10.7 nM, respectively). The voltage-dependent steady-state parameters of potassium channel gating are unaffected by the toxin in both channels, but due to the fast association and dissociation kinetics the toxin slows the rate of inactivation of Kv1.3/KCNA3 channels. Expressed by the venom gland. Has the structural arrangement of an alpha-helix connected to antiparallel beta-sheets by disulfide bonds (CS-alpha/beta). This toxin has no effects on Kv1.1/KCNA1, Kv1.4/KCNA4, Kv1.5/KCNA5, Kv11.1/KCNH2, KCa3.1/KCNN4, BK/KCNMA1, and Nav1.5/KCNA5 (when tested at 10 nM). Belongs to the short scorpion toxin superfamily. Potassium channel inhibitor family. Alpha-KTx 04 subfamily.