Table 2.

Redundancy of PPIs.

Species	Proteins	Interactions	>1 publication	>1 method	>1 database
C. elegans	3,173	5,300	668 (13%)	155 (3%)	4,536 (86%)
D. melanogaster	7,529	24,811	198 (1%)	298 (1%)	17,904 (72%)
H. sapiens	10,397	51,308	9,358 (18%)	21,036 (41%)	26,263 (51%)
S. cerevisiae	5,806	69,059	12,037 (17%)	17,219 (25%)	29,053 (42%)

The total number of proteins and interactions (that could be mapped to Ensembl gene identifiers), as well as the number of interactions reported by more than one publication, more than one method or more than one database, is shown. Relative numbers were obtained through normalisation with the total number of interactions.