Illustration of classifying residues within map kinase, 1DI9. A: The line plot below indicates the AUC at each position along the chain. The arrows indicate the locations in the sequence with AUC above 0.90. These classifying residues are shown in green on the structure. 1DI9 illustrates the underlying reason for classification. The good classifiers form a core that is surrounded by the ATP binding site (in yellow), the peptide binding channel (in gray), and the residues that, when phosphorylated, activate the enzyme (in red). Additionally, LYS53 directly interacts with the ATP ligand. Interestingly, residues ASN82, VAL83, and LYS165 form another environment that classifies the function well. They are directly behind the peptide binding channel and are in close proximity to the ATP binding site. B: ROC of the ranked chains outputted from the congruence approach. Of the 27 members in our dataset, the first 25 chains ranked were true positives, whereas the method failed to recognize 1KOA and 1FMK as structurally similar (AUC is 0.935).