The question is how exactly does it regulate the activity and how does it activate this enzyme? So what happens is, if we examine a single one of these regulatory chains each regulatory chain contains one, two allosteric sites. So we have one, two, and two here. So we have 1234 of these regulatory sites that the cyclic adenosine monophosphate can actually bind to. Now, once that CMP binds onto all of these regulatory sites so we have four CMP molecules binding to four of these sites. What happens is that creates a conformational change that allows the R two complex.