Blocks human voltage-gated potassium channel Kv1.2/KCNA2 (IC(50)=3.6 nM) and Kv1.3/KCNA3 (IC(50)=72 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 voltage-gated potassium channel Kv1.1/KCNA1, intermediate conductance calcium-activated potassium channel KCa3.1/KCNN4 or the Shaker IR (with inactivation domain removed). Belongs to the short scorpion toxin superfamily. Potassium channel inhibitor family. Alpha-KTx 10 subfamily.