Abstract As a pore-forming toxin, activation, oligomerization and pore-formation were both required for the mode of action Cry toxins. Previous results revealed that helices α4–α5 Domain I involved in Cry2Ab, however, key residues Cry2Ab aggregation remained ambiguous. In present studies, we built 20 alanine mutants site-directed demonstrated N151A, T152A, F157A, L183A, L185A I188A could reduce...