Acts as a copper chaperone by delivering 2 Cu(+) ions to CopY Zn(2+)-bound form. This transfer results in displacement of zinc and dissociation of CopY from the promoter, allowing transcription of the copYZAB operon. Monomer in the absence of copper. Homodimer or homooligomer in the presence of copper ions. Interacts with the copper ATPase CopA. Interacts with CopY via a charge-based interaction. By Cu(+) and Cu(2+). Controlled by copper-induced proteolysis.