 Although this region is evolutionary conserved in the spiders family, it has remarkable differences with other ICK-like proteins.One of the special characteristics is that Dc1a contains an additional disulphide bond that links cysteine 42 with cysteine 45 and stabilizes the serine-rich hairpin loop.Another feature is a unique three-standard antiparallel β-sheet in the amino-terminal region which is formed by an unusually large loop between cysteine 26 and cysteine 40.