Copper-sensing transcription factor that regulates iron uptake genes. Under copper starvation conditions activates the transcription of the copper transport genes, ctr4, ctr5 and ctr6. Cytoplasmic in presence of excess copper ions. The Cys-His motif (328-342) interacts with the N-terminal nuclear localization signal region leading to sequestration in the cytoplasm. Nuclear under copper starvation conditions.