The cadherin-like protein is essential to specificity determination and cytotoxic action of the Bacillus thuringiensis insecticidal CryIAa toxin

The Bacillus thuringiensis CryIAa toxin binds a cadherin-like protein (BtR175) on the brush-border membranes of the Bombyx mori midgut columnar cells, which are the targets, By introducing the BtR175 gene with a baculovirus, Spodoptera frugiperda Sf9 cells expressed BtR175 protein on the cell membrane and became susceptible to the CryIAa toxin, The toxin bound the cadherin repeat adjacent to the membrane and made a pore that passed inorganic ions, causing the cell to swell and burst, This was not observed with a BtR175 variant lacking the toxin-binding site. This in vitro experiment mimicked the specific insecticidal action of the toxin in vivo well. (C) 1999 Federation of European Biochemical Societies.