Sickling occurs in deoxyhemoglobin, but not in oxyhemoglobin. Normal deoxyhemoglobin (HbA and HbS) molecules have a small hydrophobic "pocket" on the surface of a ? chain. In oxyhemoglobin, however, this pocket is located toward the interior of the hemoglobin molecule. From what you know about the sickle-cell mutation and disease, determine which two amino acids make up this pocket.
1. Valine
2. Glutamate
3. Glutamine
4. Phenylalanine
5. Lysine