So one of these units we call the other unit we call the actually, as we see in this particular diagram we have two nineteen S units that flank the 20s subunit on both sides. Now, the, as we'll see in just a moment are actually regulatory units and it's the that basically catalyzes the breakdown of the protein. Now, if we zoom in on this twenty S unit we basically find this structure here. So we have two types of subunits that make up this core structure. We have the alpha subunit and we have the beta subunits. So we have seven alpha subunits shown here and seven alpha subunits shown here.