Figure 1

Distribution of interacting proteins with respect to the (a) structure-based functional similarity, (b) annotation-based functional similarity and (c) functional consistency. The interaction data from the MIPS, DIP and BioGRID databases were used. The functional categories and annotations were obtained from FunCat in MIPS. (a) The functional similarity of each interacting protein pair was measured by the maximum structure-based similarity of the pair-wise functions they have in a hierarchy. More than 60% of interacting pairs have the functional similarity less than 0.4. (b) The functional similarity of each interacting protein pair was also measured by the maximum annotation-based similarity of the pair-wise functions they have. Around 60% of interacting pairs have the functional similarity less than 0.2. (c) The functional consistency of each interacting protein pair was finally measured by the proportion of the common functions they share. As similar to the distribution in (b), more than 60% of interacting pairs have the functional consistency less than 0.2.