Figure 3

Confidence scores for human protein-protein interactions (PPIs). a) Confidence scores calculated based on a GO semantic similarity score [36]. We determined cut-off scores at 0.2 and 0.6 to divide low-, medium- and high-confidence PPIs. b) For PPIs in humans where detailed information was available for the interacting proteins, we also calculated another confidence score with the PRINCESS PPI-evaluation tool [37]. By default, PRINCESS sets it cut-off score at 2.0. More than the half (52.9%) of the evaluated PPIs were above this value.