Feature set derived for pairwise protein-protein interaction prediction in human. We collected a total of 27 features from 8 different data sources. The first column lists the feature expert to which the feature source was attributed to. Unlike yeast, for human we had a total of three experts: F, E and S (for definition see the 'Feature' section). The second column lists the name of the feature source. The third column lists the number of attributes from each source. The fourth column presents the average percentage of pairs for which information is available using this feature source.