A luminal loop of Wilson disease protein binds copper and is required for protein activity

The copper-transporting ATPase ATP7B is essential for loading of copper ions to copper-dependent enzymes in the secretory pathway; its inactivation results in Wilson disease. In contrast to copper ion uptake by the cytoplasmic domains, ATP7B-mediated copper ion release in the Golgi has not been explored yet. We here demonstrate that a luminal loop in ATP7B, rich in histidine/methionine residues, binds reduced copper (Cu(I)) ions and identified copper-binding residues play an essential role in ATP7B-mediated metal ion release.

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