Neurotoxin. Causes spastic paralysis and death in mice. Moderate inhibitor of L-type calcium channels (Cav1/CACNA1). Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Belongs to the neurotoxin 10 (Hwtx-1) family. 53 (PNTx27C4) subfamily.