Blocks voltage-gated potassium channels Kv1.1/KCNA1 (IC(50)=203.15 pM), Kv1.2/KCNA2 (IC(50)=8.92 nM) from rat and human Kv1.3 KCNA3/KCNA3 (IC(50)=171 pM) potently. At 2 uM, also blocks Shaker IR and has a moderate effect on rat Kv1.6/KCNA6. 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 no effect on rat Kv1.4/KCNA4, Kv1.5/KCNA5, Kv4.1/KCND1 or human Kv11.1/KCNH2 and Kv3.1/KCNC1. Belongs to the short scorpion toxin superfamily. Potassium channel inhibitor family. Alpha-KTx 03 subfamily.