The protein encoded by this gene is a copper-containing glycoprotein found soluble in the serum and GPI-anchored in other tissues. It oxidizes Fe(II) to Fe(III) and is proposed to play an important role in iron homeostasis. In humans mutations of this gene cause aceruloplasminemia, which is characterized by retinal degeneration, diabetes, anemia and neurological symptoms. In mouse deficiency of this gene in combination with a deficiency of its homolog hephaestin causes retinal degeneration and serves as a pathophysiological model for aceruloplasminemia and age-related macular degeneration. Alternative splicing results in multiple transcript variants that encode different protein isoforms.