The transferases involved with Escherichia coli are very similar in some respects, yet still remain remarkably different in others. All three enzymes have differing numbers of domains. While the aminotransferase contains three domains, the phosphotransferase contains two, and the sulfurtransferase only one. The substrates that interact with the active sites of the domains differ as well. Three different elements compose the ligands that are recognized by these active sites - nitrogen, phosphorus, and sulfur. The mechanisms governing the processing of the ligand in the active site are also very different. While the mechanism for the phosphotransferase is remarkably simple, the mechanism involved with the aminotransferase is extremely complex. Even the amount of substrate processed by each enzyme varies, as was shown in the various images throughout this site. With so many marked differences between the enzymes, it is no small wonder why these enzymes share nearly no sequence homology with one another (less than 20%).

However, while there are many differences between these three enzymes, some similarities do still exist. All three enzymes, as was shown, are transferases, responsible for the exchange of groups of atoms from one molecule to another. There are also many similarities in structure and function between these enzymes. Both the aminotransferase and the phosphotransferase contain polar groups within their active sites, helping to bind the ligand to the site. All three enzymes contain a similar ratio of sheet to helix structure. The mechanism responsible for the processing of the ligand in aminotransferase and phosphotransferase requires a strategy called nucleophilic attack.

These enzymes are important not only to E. coli, but to our total overall understanding of how this class of enzymes function. Many of the mechanisms for substrate processing are conserved across species, so understanding the processes of this simple organism can help to enlighten those who investigate mechanisms involved with higher order beings. A simple organism, filled with complex machinery, E. coli can be an important tool in understanding how the basic building blocks of life work in other organisms.