Now, what actually happens when these two regions are phosphorylated? So this beta submune and the other beta submune well, remember, what the tyrosine protein kinase does is it phosphorylates. It attaches a phosphoryl group onto tyrosine residues and some of these tyrosine residues that are phosphorylated actually begin to act as attachment points for other proteins namely an important protein known as IRS which stands for insulin receptor substrate. So one of the phosphorylated tyrosine residues on the insulin receptor more specifically this one over here basically attracts a protein called the insulin receptor substrate or simply IRS. And once the IRS and in this particular case, we call it IRS One because we actually have another one called IRS Two which exists in a different pathway that we're not going to look in this lecture. But IRS One basically attaches onto this phosphorylated residue and once it is attached because it moves in close proximity to the active side of that activated receptor kinase.