Lethal neurotoxin. Causes spastic paralysis and death in mice in 4-6 min after intracerebroventricular injection at dose levels of 1.5 ug per mouse. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Belongs to the neurotoxin 04 (omega-agtx) family. 02 (Tx1) subfamily.