One of three inter-subunit interface formed by α 2 and α 3 of a Cry4Aa monomer interlocking with α 4 and α 6 of an adjacent Cry4Aa monomer within the pre-pore trimer. (a) side view (b) top view of three hairpins of α3 and α4 in Cry4Aa trimer. The hairpins are rendered as ribbons and colored blue for M1, red for M2 and green for M3, (c) three 120°-side views of amino acid residues at the interface between α2 and α3 of M3 (cyan and green) and helices α4 and α6 of M1 (red) with the three α3-α4 hairpins shown in transparent, and (d) Four 90°-side views of the interlocking between α3, α4 and α6 by Group 1's residues. Residues on α2 of M3 are colored cyan and that of α6 are colored purple. Residues of Groups 1 and 2 from Table 1 are depicted in vdW and stick representations, respectively.