Serine protease inhibitor homolog that blocks voltage-gated potassium channels (Kv1.1/KCNA1, Kv1.2/KCNA2, and Kv1.6/KCNA6) (IC(50)=0.13-50 nM). Expressed by the venom gland. LD(50) is 38 mg/kg by intravenous injection. Does not inhibit serine proteases. Belongs to the venom Kunitz-type family.