So NMP kinase molecules, for example adenylate kinase or guanylate kinase. So guanylate kinase basically catalyzes the transfer of the phosphoryl group from GTP onto some type of NMP. So if we study the three dimensional structure of all these different types of NMP kinases, for example, these two, we're going to see a region that is conserved. It remains the same when we go from one molecule, one enzyme, one kinase to another kinase. And this is the region shown here. So if we begin at the beginning of the polypeptide chain, this is where we're going to be.