All organisms have molecular systems that function to maintain metal ion homeostasis. The P1B-type ATPases are membrane-bound ion transporters responsible for the efflux of heavy metals and are essential for controlling the cellular levels of beneficial metals like copper and zinc and removing toxic ones like cadmium and lead. Malfunctioning copper ATPases in humans result in inherited neurological disorders like Menkes' syndrome and Wilson's disease. The Wilson ATPase has also been implicated in promoting resistance to the anticancer drugs cisplatin and carboplatin. The mechanisms of metal transport across membranes by these ATPases are not well understood. The goal of this proposal is to crystallize and determine the structure of CopA from A. fulgidus, a well characterized copper transporting P1B-type ATPase with strong identity to both the Menkes' and Wilson's proteins. Structural characterization of CopA will help to elucidate the mechanism of copper transport across cell membranes and will provide new insight into its human homologues that may be relevant to the treatment of disease and the improvement of platinum based antitumor drugs. The structure of a P1 B-type ATPase will be the first of its kind.