Figure 4

Interactions among functional groups of proteins. Each row and column of the shown profile corresponds to a protein-protein interaction (two-hybrid) count with different functional classes (see matrix). The interactions within certain functional classes are enriched compared to other functions groups, e.g. head assembly proteins show 15 interactions among each other, 8 interactions are detected between tail assembly proteins and 3 interactions among proteins of unknown function (see Additional file 1: Tables S4 and S5 for details).