Synergistic toxin that induces or increases a cytolytic effect when combined with CSTX-1 (AC P81694) or CSTX-9 (AC P58604). When alone, has a weak insecticidal activity, with an unknown molecular target. Heterodimer of A and B chains; disulfide-linked (By similarity). Interacts with CSTX-1 (AC P81694), and with CSTX-9 (AC P58604) (By similarity). Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Belongs to the neurotoxin 19 (CSTX) family. 12 subfamily.