Hemoglobin subunit alpha; Hemoglobin subunit beta (HBA (for Hemoglobin subunit alpha), HBB (for Hemoglobin subunit beta))

Hemoglobin subunit alpha and hemoglobin subunit beta are the two major polypeptide chains that make up adult hemoglobin (HbA), the principal oxygen-carrying molecule in vertebrate red blood cells[1][2][3][7]. Each hemoglobin molecule is a tetramer consisting of two alpha (HBA) and two beta (HBB) subunits, each holding a heme group that reversibly binds oxygen[2][3]. The alpha and beta subunits are encoded by the HBA and HBB genes, respectively[4]. The quaternary structure of adult hemoglobin, and the coordinated binding and release of oxygen (cooperativity), are critical for its physiological function[1][3][5]. Mutations in HBB and, less commonly, HBA are responsible for a range of hemoglobinopathies, including sickle cell disease (primarily HBB, resulting in hemoglobin S) and thalassemias[4][6][7]. These proteins themselves are not therapeutic drug targets in the same sense as classical receptors or enzymes but are central to the pathophysiology of several diseases and influence drug responses in hemoglobinopathy treatments[4][6][7]. Notes on correctness: - The combined entry "Hemoglobin subunit alpha / Hemoglobin subunit beta" groups two distinct but closely interacting proteins and is not a single molecular target; best practice is to treat them as “Hemoglobin subunit alpha” and “Hemoglobin subunit beta” individually[1][4]. - These are not "receptors" or classical therapeutic targets, but essential components of the hemoglobin tetramer involved in oxygen transport; however, drugs are approved that target the consequences of their mutations (like in sickle cell disease)[4][6][7].

Other names

alpha-globinbeta-globinHBAHBBHemoglobin alphaHemoglobin beta

Inhibition of hemoglobin S polymerization (e.g., Voxelotor); Induction of fetal hemoglobin (e.g., Hydroxyurea increases γ-globin, replacing β-globin in part); Reduction of hemolysis and vaso-occlusive episodes via indirect effects