A Copper Story: From Protein Folding and Metal Transport to Cancer
Enzymes need to fold into unique three-dimensional structures in order to function. Copper ions are cofactors in many essential enzymes. Such enzymes need to couple polypeptide folding with metal incorporation, as the metal sites are often integrated within the folded structure. Since free copper ions are toxic, most organisms have highly specialized copper transport systems. The human cytoplasmic copper chaperone Atox1 delivers copper to P-1B-type ATPases in the Golgi, for incorporation into copper-dependent enzymes following the secretory path. Copper plays key roles in cancer development, as copper-dependent enzymes are needed for tumor growth and metastasis. In addition, platinum-based drugs are exported out of cells by the copper transport machinery. Recent findings also imply that some copper transport proteins regulate cell growth and development. In this brief journey of my later career, I will discuss the roles of copper in protein folding, mechanisms of copper ion transport, and cisplatin hitchhiking. The identification of new partners for Atox1 underscore the importance of further research in this area for combating cancer.