Structures of members of this family show that they are comprised of a triple-stranded antiparallel beta-sheet connected by three disulfide bridges, which defines this as a novel family of serine protease inhibitors [1,2].

1: Structural and functional properties of a novel serine protease inhibiting peptide family in arthropods. Simonet G, Claeys I, Broeck JV; Comp Biochem Physiol B Biochem Mol Biol 2002;132:247-255. PMID:11997226

2: Complexation of two proteic insect inhibitors to the active site of chymotrypsin suggests decoupled roles for binding and selectivity. Roussel A, Mathieu M, Dobbs A, Luu B, Cambillau C, Kellenberger C; J Biol Chem 2001;276:38893-38898. PMID:11495915