What that means is it binds onto a location that is different than where oxygen binds to, and it creates some type of change in the function in the affinity of that hemoglobin molecule for oxygen. Now, before we discuss where that molecule actually binds to, let's recall one important fact about deoxyhemoglobin. So, deoxy hemoglobin exists in the T state, in the ten state. And one fact about the T state is it's very unstable. So in the absence of the two three BPG molecule, there is a pocket, there is this space that is formed at the center of the deoxy hemoglobin. And inside that space, there is electrostatic repulsion that takes place between the amino acids on the beta one and the beta two subunits.