Figure 7.

Valence of proteins in the interaction graphs and sequence conservation levels are positively correlated. (a) Genes from the presynaptic 120 genes (PS120) list were measured for their sequence conservation (percentage sequence identity between insects and human) and for the valance of each protein. The number of proteins for each sequence identity range is indicated in parenthesis. The number of protein partners for each PS120 is provided in Additional data file 5. Note that a positive correlation between the protein conservation index and the protein valance is evident only at highly conserved sequences (>50% identity). (b) Data from protein complexes (coatomer protein [COP]-1 and peroxin biogenesis [PEX]) follow a similar trend as the PS120. Proteins of each complex were divided into groups according to their sequence identity level (low [L], medium [M], and high [H]). The number of proteins in each group is indicated in parenthesis. PEX (16 proteins, including the 14 core PEX proteins; Figure 4) are weakly conserved between human and insects, while COP-1 (nine proteins; Figure 3a) exhibit a stronger conservation index. Note that the PEX and COP-1 proteins are not included in the PS120 set.