Figure 1.

Tissue-specific and recently evolved proteins make few protein interactions. (A) Integrating protein interaction and expression data to construct ‘local' interactomes for human cells and tissues. (B, C) The relationship between protein interaction degree and protein expression breadth (the number of tissues in which a protein is expressed) for the complete human protein interaction network (B), and (C) for ancestral (pre-metazoan) proteins (blue) and for metazoan-specific proteins (red). P<10e−15 in all cases, Kolmogorov–Smirnov test. Bars indicate one standard error. Interaction degree is the maximum number of co-expressed interaction partners. The same analysis is performed for the multiple-support network and for a network without protein complex-derived interactions in Supplementary Figure 1.