Tetramer consisting of 2α and 2β chains. Each chain enfolding a haem moeity. Oxygen reversibly binds to the ferric(Fe2+) iron molecule.
Exterior is highly polar (water soluble), whilst interior hydrophobic.
Most important purpose = oxygen transport.
Genotypes --> HbA;2α2β, HbA2;2 α2δ, HbF;2 α 2 ϒ
Normal concentrations HbA – 95%, HbA2 – 2.5%, HbF – 2.5%