Analysis of Bacillus thuringiensis toxin Cry1Ac binding proteins in midgut brush border membranes of Trichoplusia ni larvae

Specific binding of Bacillus thuringiensis (Bt) Cry toxins to the insect midgut brush border is a key event in the action of Bt toxins in insects, and alteration of this specific binding is a major mechanism of Bt resistance in insects. To understand the molecular interactions of Bt toxin Cry1Ac with the midgut of Trichoplusia ni larvae, Cry1Ac binding proteins from brush border membranes of T. ni larvae were analyzed by Cry1Ac toxin affinity chromatography. Putative Cry1Ac binding proteins were further examined using immunological, biochemical and proteomic methods.