Copper-binding proteins are specialized proteins that play a crucial role in transporting and storing copper ions within the body. Copper is an essential trace element necessary for various biological functions, including energy production and the formation of connective tissues. These proteins help maintain copper homeostasis, ensuring that the levels of copper are balanced and that excess copper does not become toxic. Examples of copper-binding proteins include ceruloplasmin, which carries copper in the bloodstream, and metallothioneins, which help in detoxifying excess copper. Proper functioning of these proteins is vital for overall health, as imbalances can lead to conditions such as Wilson's disease or Menkes disease.