Now, the question is where exactly does the CTP molecule actually bind to on the atcase? Well, can the CTP bind onto the active side of this enzyme? The only way to bind onto the active side is if the CTP actually resembles has the same structure as either aspartate or carbon oil phosphate. And we know that the structure of this looks nothing like the structure of either of these two substrates. And so what that means is for CTP to actually inhibit the activity of atcase it must bind onto some other side other than the active side. And those sites, as we said previously, are known as allosteric sites, regulatory sites.