Table 2.

Pair-wise overlap of annotations for human–mouse, human–rat, human–pig and mouse–rat

Resource/annotation	Human–mouse	Human–rat	Human–pig	Mouse–rat
eggNOG mammalian orthology
Common 1-to-1 groups	12 736	11 038	10 916	12 157
Common groups	15 094	13 429	13 573	14 155
Gene Ontology annotations
Experimental	15 215	4 680	133	3 754
Author statement	1 433	494	2	193
Inferred	50 473	39 740	18 751	64 879
Electronic	25 632	12 430	15 054	13 937
High-scoring STRING protein-protein interactions
Experimental	537	72	672	66
Experimental transferred	10 422	6 705	9 290	10 859
TISSUES expression data
Tissues covered by experimental data	19	12	20	12

For each of the selected resources, appropriate features are highlighted. For the eggNOG orthology resources, the number of common (1-to-1) mammalian orthologous groups are reported. For the Gene Ontology annotations and the high-scoring (overall confidence score above 0.7) STRING protein–protein interactions, the number of associations shared between a pair of organisms was determined using the eggNOG mammalian orthology. For the TISSUES 2.0 database, the number of tissues (out of the 21 main tissues) covered by an experimental dataset in both organisms are reported.