Inhibitor of voltage-gated potassium channels of the Kv4/KCND family. Inhibition of Kv4.3/KCND3 and Kv4.2/KCND2 is strongly voltage-dependent, while inhibition of Kv4.1/KCND1 shows less voltage-dependence. Its binding site may be near the potassium channel voltage sensor. Also blocks calcium channels. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Has no affinity for Kv1.4/KCNA4, Kv2.1/KCNB1, and Kv3.4/KCNC4. Belongs to the neurotoxin 10 (Hwtx-1) family. 19 (HpTX2) subfamily.