Toxicity, binding and internalization of the pea-A1b entomotoxin in Sf9 cells

PA1b (Pea Albumin 1b) is a peptide toxin lethal for certain insects. This paper shows that the cultured insect cells Sf9 are sensitive to the toxin and display a high-affinity binding site for PA1b. Mammalian cells are not sensitive and no binding activity was detected. Signs of apoptosis of the Sf9 cells were observed in response to the toxin. The use of this cellular model also demonstrated that PA1b was internalized in the cells, via the binding site, raising the new question of the role of this toxin within the cell, and of the mechanisms leading to cell death.