Chaperone that serves for the intracellular sequestration and transport of Cu(+). Delivers Cu(+) directly to the transmembrane transport sites of copper-exporting P-type ATPase A (CopA). Probably has a redox function due to the presence of a 2Fe-2S cluster and could reduce Cu(2+) to Cu(+). Binds 1 [2Fe-2S] cluster per subunit. Homodimer or homooligomer in the presence of copper ions (By similarity). Monomer in the absence of copper. Interacts with CopA probably in its Cu(+)-bound form.