Copper Transport: An Overview

ConclusionsCopper transport continues to show unexpected and, in some cases, surprising departures from traditional mechanisms. Although both iron and copper bind to plasma proteins, the recent data suggest that each works through separate and distinct mechanisms for gaining access to cells. Ceruloplasmin and albumin as postulated transport carriers have withstood the test of time. One must concede, however, that there may be other serum proteins that perform a copper transport function. One thought not to be forgotten is that in postulating specific transport proteins for copper, one is showing an "animal bias."Plants and some microorganisms also require copper, but there have yet to be found specific proteins that perform copper transport functions in these organisms. There is an immediate and pressing need to clarify the nature of the component(s) that conveys copper ions through the cell membrane. We stand to learn how copper is shielded from doing harm to membrane components and perhaps apply this information to other aspects of copper metabolism. The multifaceted nature of a copper transport mechanism seems to find unity at the membrane surface. Ceruloplasmin, working through specific receptors and membrane dissociating agents is able to convey copper atoms to cells. Similarly, albumin, utilizing complexes with amino acids, conveys copper ions to the membrane transports. The transport, in turn, may show different recognition functions depending on cell type. There is always the concern that copper may "borrow" an existing transport system for its own transport purposes. Diseases like Menkes'syndrome rule against this possibility and tend to fortify the belief that copper transport is unique and of its own.