Figure 1

The illustration of a concept of overlap in a molecular network. For a pair of paralogs the overlap Ω is defined as the number of their common neighbors in the network. In the case of a transcription network the (upstream) regulatory overlap Ω _reg is given by the number of transcription factors regulating both paralogs, while for the physical interaction network the interaction overlap Ω _int counts their common binding partners. The pair of paralogs used in this illustration has the overlap Ω = 2 out of the total of 5 distinct neighbors of the pair. That corresponds to a normalized overlap of 2/5 = 0.40.