Figure 7From: The impact of horizontal gene transfer in shaping operons and protein interaction networks – direct evidence of preferential attachmentDistribution among the COG categories for those E. coli genes that are members of proten-protein interaction network. Counts were estimated for each evolutionary gene category, and expressed as percentages per total number of genes per COG category. The Core, Non-core and HGT gene sets contained within the protein interaction network differ in their distribution of COG functional categories (P-value < 0.001).Back to article page