We are taking a look at cross-species pharmacological parameters such as IC50s and Ki for selected receptor and enzyme pairs for the same compound. So a) has anyone done this ? and b) can anyone point to recent statistics on orthology between species pairs, expressed as the average % aa identity between their proteome sets? (I don't want to have to compute this de-novo but would rather appreciate pre-cooked or published results). I'm interested in pharmacologocally popular organisms e.g. human/mouse/rat/hamster/rabbit/pig with zebrafish as outgroup. It would also be great if anyone has ever gone down this route to the target-level e.g. to show, on average for example, rodent GPCRs had less(or greater) % identity than say kinases? There was some useful data in the original mouse genome paper quoting the 12,845 pairs of mouse-human 1:1 orthologues at 70% identity which rose to 90% for the 700 odd disease genes at that time but this was back in 2002 (and seems on the low side?) http://www.ncbi.nlm.nih.gov/pubmed/12466850