And this bond here is known as the isopeptide bond. So the carboxyl terminal group of the ubiquitous is extended and it contains a glycine residue and it's this glycine residue that is covalently attached onto the epsilon amino group of lysine residues found on target proteins. And this bond is known as the isoppeptide bond. Now, as we will see in just a moment, the formation of this isopeptide bond is carried out by the hydrolysis of an ATP molecule. So we have to hydrolyze an ATP molecule to actually gain enough energy to carry out this process by which we attach a Ubiquitin onto that target protein. So in this lecture, we're going to look at the process by which we attach Ubiquitin onto the target protein.