Dual-function toxin that inhibits both serine proteases (trypsin Kd=124 nM) and voltage-gated potassium channels rKv1.1/KCNA1 (IC(50)=0.9 nM). The activity on the Kv1.1/KCNA1 is selective and reversible. The toxin presumably acts by blocking the channel pore in the open state. Does not inhibit voltage-gated potassium channels Kv1.2/KCNA2, Kv1.3/KCNA3, Kv1.4/KCNA4, Kv1.5/KCNA5, Kv1.6/KCNA6, Kv2.1/KCNB1, Kv3.1/KCNC1, Kv4.2/KCND2, Kv4.3/KCND3, hERG, Shaker, HCN1, HCN2 and voltage-gated sodium channels Nav1.2/SCN2A, Nav1.3/SCN3A, Nav1.4/SCN4A, Nav1.5/SCN5A, Nav1.6/SCN8A, Nav1.7/SCN9A, Nav1.8/SCN10A and the insect channel DmNav1. Belongs to the venom Kunitz-type family. Sea anemone type 2 potassium channel toxin subfamily.