Potassium channel blocker. At 3 uM, this toxin blocks voltage-gated potassium channels rKv1.2/KCNA2 (5%), hKv1.3/KCNA3 (10%),rKv1.4/KCNA4 (20%), Kv11/hERG (24%), and Shaker-IR (27%). Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Is completely devoid of the classical secondary structure elements (alpha-helix and/or beta-strand). Does not block voltage-gated potassium channel rKv1.1/KCNA1, rKv1.5/KCNA5, and rKv1.6/KCNA6. Belongs to the short scorpion toxin superfamily. Potassium channel inhibitor family. Epsilon-KTx 01 subfamily.