Now, the alpha unit is attached onto the beta unit by a disulfide bridge shown here. So we have one bridge shown here and another bridge shown on that adjacent identical chain. Now, what exactly is the function of the alpha and the beta units? Well, the two alpha units, which are, by the way, found on the outside of the cell, the extracellular environment basically create the pocket, the region of space that binds the insulin. And so that exists on the outside of the cell. Now, these beta submunes not only spam the entire membrane shown here, but they also have components found on the inside the cytoplasmic side of the cell.