Comparison of positions in the lipid bilayer of homologous toxins calculated by different methods. Cardiotoxin A5 (A, D), cardiotoxin A1 (B, E) and cytoxin 1 (C, F) were calculated byPPM (A-C) or by Monte Carlo Simulations (D-F) in the hydrophobicslab. Coordinate sets of the toxins were kindly provided by Dr. Efremov . The backbone of toxins is shown in ribbon model. Hydrocarbon core-penetrating residues are shown in stick model. Hydrocarbon core boundary at the extracellular side is indicated by red dots. The layer of lipid phosphates ("P") is shown by gold dots (at 5 Å outside the hydrocarbon boundary). The center of membrane is indicated by grey dots (at 15 Å inside the boundary). The orientations of each protein obtained by PPM and MC simulations are rather similar; and sets of membrane-penetrating residues are identical. However, the tilt between the protein axis and the membrane normal differ by 3° for 1rl3, by 10° for 1kxi and by 25° for 2cdx.