Estimated probability for same cellular role as function of similarity for orthologs and paralogs. These probabilities were estimated as the overlap integral of the ProtFun predictions for H. sapiens and D. melanogaster proteins involved in each pair. The probabilities could not be reliably estimated outside the range 30%-80% identity as orthology versus paralogy cannot be reliably predicted for distant homologs and because very closely related paralogs are likely predicted to be orthologs.