Ceruloplasmin is a blue, copper-binding (6-7 atoms per molecule) glycoprotein. It has ferroxidase activity oxidizing Fe(2+) to Fe(3+) without releasing radical oxygen species. It is involved in iron transport across the cell membrane (By similarity). 4 Fe(2+) + 4 H(+) + O2 = 4 Fe(3+) + 2 H2O Binds 6 Cu cations per monomer. Expressed by the liver and secreted in plasma. Also expressed in the hypothalamus, spleen and uterus. No expression in the cortex, heart, intestine or kidney. Belongs to the multicopper oxidase family.