Acts as a gating-modifier to inhibit voltage-gated potassium channels. It inhibits delayed Kv2.1/KCNB1 (IC(50) is 12.7 nM), Kv2.1/Kv9.3 (IC(50) is 7.2 nM) (KCNB1/KCNS3), Kv2.2/KCNB2 (IC(50) is 21.4 nM), and transient Kv4.2/KCND2 (IC(50) is 1.2 nM) channels. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. This toxin does not have effect on Kv4.1/KCND1 and Kv4.3/KCND3. Intracerebroventricular injection into mice does not induce observable neurotoxicity symptoms (PubMed:12065754). Belongs to the neurotoxin 10 (Hwtx-1) family. 57 (ScTx1) subfamily.