And this takes place in the cytoplasm of our red blood cells. And so we actually find bicarbonate ions dissolved in our cytoplasm and in our blood. And so in the first step, what we do is we essentially activate that bicarbonate molecule to form this carboxy phosphate intermediate. So we transfer of a spoil group from the ATP onto this bicarbonate to form this carboxy phosphate. And the reason we have to carry this step out is to actually prepare that molecule to bind that CO2 molecule onto that biotin because without this step, the CO2 would simply not be able to bind onto that binding site of that enzyme. So once again, recall that carbon dioxide exists as bicarbonate ions in the cytoplasm and in our fluids of the body.