Inhibits voltage-gated potassium channels of the subtype Kv4.1/KCND1 with high affinity and shows weak effects on Kv4.2/KCND2 and Kv2.1/KCNB1 subtypes. The toxin modifies the gating behavior of the channel and may interact with the S3-S4 extracellular loop. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. This toxin does not inhibit Kv1.1/KCNA1, Kv1.2/KCNA2, Kv1.3/KCNA3, Kv1.4/KCNA4 and Kv3.1/KCNC1 potassium channels. Belongs to the neurotoxin 30 (phrixotoxin) family.