Potent inhibitor of the Shaker potassium channel (Ki=0.16 nM) and its mammalian homologs (Kv1.3/KCNA3 (Ki=1.7 nM), Kv1.1/KCNA1 (Ki=136 nM), Kv1.6/KCNA6 (Ki=149 nM)). Expressed by the venom gland. Has the structural arrangement of an alpha-helix connected to antiparallel beta-sheets by disulfide bonds (CS-alpha/beta). Does not block Kv2.1/KCNB1 (Ki >2000 nM). Belongs to the short scorpion toxin superfamily. Potassium channel inhibitor family. Alpha-KTx 03 subfamily.