So we have four beta shown in orange. We have these four gamma, the four delta and the four alpha. Now, only these green structures, the gamma structures actually have catalytic activity and these green structures are the ones that are responsible for catalyzing this particular step. But the other three subunits basically have regulatory abilities. And as we'll discuss in just a moment, it's the beta subunits and the delta subunits which are ultimately responsible for fully activating the phosphorylase kinase. So during times of rapid and sudden strain use activity, we know that our body begins producing and releasing hormones into our bloodstream.