Successful prediction of protein-protein binding site residues for a bacterial homolog of human Rhesus protein Rh50 (PDB entry 3B9W). The protein forms a homotrimeric complex; two subunits are shown in green and yellow ribbon representation. The surface of one subunit is colored according to the probability ratio for each surface residue. The colors vary continuously from blue to white to red for low, neutral (1.0), and high ratios, respectively. The two figures differ by a 180° rotation about the vertical axis. The red high confidence predicted binding site residues are correctly located in the actual binding site and the blue high confidence non-binding site residues are located on the opposite face. The boundaries of the membrane are shown in purple.