Summary of predictive performance and expected performance on proteins of unknown function. The first 13 columns show the AUCs for each functional class in each of the 7 × 7 species-species transfers. The order of functional classes and species is the same as in figure 1. The 14th column shows the corresponding species-species discrimination AUCs (from Figure 3) and the 15th column the distinction between known and unknown proteins for the species from which the classifier is derived (from Figure 2). To predict the expected performance on proteins of unknown function, find the species-species contrast that corresponds most closely to the known-unknown contrast of interest. The corresponding function prediction AUCs should give a reasonable estimate for the expected performance. It can be seen here that functional classes that are easily distinguished within a species will also successfully transfer between species, and such predictors (e.g. 'transport and binding', column 13) will also yield reliable results on the proteins of unknown function.