Inhibits voltage-gated sodium channels (Nav) (By similarity). Causes scratching, lacrimation, hypersalivation, sweating and agitation followed by spastic paralysis of the anterior and posterior extremities and death at dose levels of 1.62 mg/mouse. Insecticidal to the larval and adult forms of the house fly. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Belongs to the neurotoxin 03 (Tx2) family. 04 subfamily.