Studies on mechanisms of vesicular trafficking and catalysis for the Menkes (MNK) copper-transporting P-type ATPase

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Copper is an essential trace element for all organisms. Copper is needed for many processes including energy metabolism, the making and maintenance of strong bones and arteries with sufficient elasticity, the synthesis of chemical transmitters in the brain and for the reactions which remove toxic Ofree radicalsO. Copper is also used by the proteins involved in important neurological diseases including Alzheimers disease and Omad cowO disease. Menkes disease is an inherited and usually lethal copper deficiency disorder in humans, and the diverse and detrimental symptoms of this disease related to organs and tissues described above is a stark indicator of the essentiality of copper. We have carried out extensive research on Menkes disease and in particular the Menkes protein which in normal individuals plays a major role in maintaining the copper balance in cells, i.e. enough Cu to satisfy nutritional needs of cells but not too much which causes toxicity. The normal Menkes protein catalyses the transport of Cu across membranes of cells to the areas where it is needed by copper-dependent enzymes which themselves catalyse important chemical reactions. The normal Menkes protein functions as a molecular pump. We have discovered that this protein can OsenseO Cu concentrations in the cell and when these reach potentially toxic levels it can move (traffick) via small vesicles to the plasma membrane which surrounds cells. There it pumps the excess Cu out of the cell and returns to its original location. Our studies are directed to understanding the molecular mechanisms which permit this remarkable protein to achieve a copper balance in living cells. The findings will be of major significance in understanding and treating acquired and inherited diseases involving copper deficiency or copper toxicity.