Gamma chains make up the fetal hemoglobin F, in combination with alpha chains. Heterotetramer of two alpha chains and two gamma chains in fetal hemoglobin (Hb F) (By similarity). The ratio of gamma-G to gamma-A chains in is approximately 2:1 in infant chimpanzee, and 1:2 in the adult (PubMed:1342932). Red blood cells. Belongs to the globin family.