When living in Chicago, we would often get off on the 31st Street exit on Lakeshore Drive, and at the time there was a sign pointing out some parking areas for McCormick Place. I recall specifically that two of those were labeled "E2" and "E3" and being the gigantic nerd that I am, thought immediately of ubiquitin. Since it is found in every type of cell in all eukaryotic cells, the protein is appropriately named. Check out the cool ribbon model I made of ubiquitin for my students once upon a time, and then let's take a look at ubiquitin's functions in living organisms and how it contributes to health and disease.