Apoceruloplasmin: Abundance, Detection, Formation, and Metabolism

Ceruloplasmin, the main copper-binding protein in blood and some other fluids, is well known for its copper-dependent enzymatic functions and as a source of copper for cells. What is generally unknown or ignored is that, at least in the case of blood plasma and serum, about half of ceruloplasmin is in the apo (copper-free) form. This has led to some misconceptions about the amounts and variations of other copper-binding proteins and so-called free copper in the blood that might be indicators of disease states. What is known about the levels, sources, and metabolism of apo versus holo ceruloplasmin and the problems associated with measurements of the two forms is reviewed here.

Automated summary

Ceruloplasmin is the main copper-binding protein in blood, with about half existing in the copper-free form. This has led to misconceptions about other copper-binding proteins and free copper levels.