Hemoglobin subunit alpha and Hemoglobin subunit beta (HbA)

Hemoglobin is a heterotetrameric metalloprotein primarily located in erythrocytes, consisting of two alpha (α) and two beta (β) subunits, each associated with a prosthetic heme group (StatPearls, "Hemoglobin Physiology", 2023). Its fundamental biological role is the reversible binding and transport of oxygen from the lungs to systemic tissues, as well as the transport of carbon dioxide and nitric oxide (UniProt, P69905/P68871). Genetic mutations in these subunits underlie significant hematologic disorders, most notably sickle cell disease (SCD) and thalassemias. In SCD, a point mutation in the β-subunit (HbS) causes the protein to polymerize when deoxygenated, leading to red blood cell deformation, hemolysis, and vaso-occlusion (NIH, "Sickle Cell Disease", 2023). Therapeutic intervention has evolved to include direct molecular targeting; for instance, the drug Voxelotor binds to the alpha subunit to increase oxygen affinity, thereby stabilizing the oxygenated state and inhibiting the polymerization of HbS (FDA, "Oxbryta Prescribing Information", 2019).

Other names

Hemoglobin AAdult hemoglobinHBA1HBBAlpha-globinBeta-globinHemoglobin tetramer

Direct allosteric modulation of the hemoglobin tetramer to increase oxygen affinity, which stabilizes the oxygenated (R-state) hemoglobin and prevents the polymerization of deoxygenated sickle hemoglobin (HbS) (FDA, "Oxbryta Prescribing Information", 2019; PubChem, CID 71752724).