Abstract: Inhibitor cystine knot (ICK) peptides are one of the three family members of cystine knot (CK) peptides. Peptides of this kind consist of a triplet-stranded antiparallel β-sheet stabilized by three disulfide bonds to form a topological knot. They are widely distributed in animals, plants, fungi and even prokaryotes, exhibiting a diversity of biological functions including protease inhibitors, ion channel toxins, and antimicrobial, antimalarial and antiviral activities. In this article, we firstly summarized the ICK peptides found in insects with antimicrobial and ion channel toxin activities, and then introduced some neurotoxic ICK peptides in poisonous animals especially spiders and scorpions, as well as plants. These toxins usually target various ion channels of insects to exert their insecticidal activity. Finally, we discussed the evolutionary diversity of ICK peptides in combination with their gene sequence characteristics, the numbers of their domains and disulfide bonds and species distribution.

Key words: Inhibitor cystine knot, insects, antimicrobial activity, insecticidal activity; evolution