Two different forms of this protein can be detected by observing changes in magnetic susceptibility due to a paramagnetic to diamagnetic shift upon substrate binding. This protein is the target of Casgevy, which is the first FDA approved CRISPR treatment for human patients. Two versions of this protein can be distinguished from each other and tracked via BOLD (“bold”) contrast imaging during an fMRI. This protein varies its conformation in response to substrate binding via the movement of a proximal histidine residue. This protein changes its affinity in response to high concentrations of oxygen or carbon dioxide in the Haldane effect and Bohr effect, respectively. A glutamate to valine point mutation in this protein results in sickle cell anemia. For 10 points, name this protein that allows red blood cells to carry oxygen. ■END■