So notice that these two regulatory R subunits do not actually dissociate. They remain bound together. But these two green catalytic subunits basically dissociate. And so now they're activated. Because these active sites are free, they can go on and bind to all sorts of different types of substrate enzyme molecules. And once the substrate molecule binds onto the active side of that catalytic subunit, what happens is this catalytic subunit, which actually consists of these two lobes.