Has antimicrobial, insecticidal, cytolytic and cytotoxic activity. Active against E.coli DH5alpha, E.faecalis VKM B 871, B.subtilis VKM B 501, A.globiformis VKM Ac 1112, P.aeruginosa PAO1 and S.aureus 209P in submicromolar or low micromolar ranges. Lyses human erythrocytes. Kills HeLA and A549 cells. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. The N-terminal part of the mature protein (59-100) forms an alpha-helix which acts as a membrane-active peptide. It is necessary and sufficient for the toxin's antimicrobial, insecticidal, cytolytic and cytotoxic activity. LD(50) is 75 ug/g on flesh fly larvae (S.carnaria). PD(50) is 75 ug/g on M.sexta first instar larvae. Belongs to the spiderine family. Cationic/spiderine subfamily.