Acts as a chaperone to prevent the harmful aggregation of alpha-hemoglobin during normal erythroid cell development. Specifically protects free alpha-hemoglobin from precipitation. It is predicted to modulate pathological states of alpha-hemoglobin excess such as beta-thalassemia. Monomer. Forms a heterodimer with free alpha-hemoglobin. Does not bind beta-hemoglobin nor alpha(2)beta(2) hemoglobin A. Expressed in blood and bone marrow. By GATA1 during erythroid maturation. Belongs to the AHSP family.