Figure 7: Phenotypic analysis of mitochondrial Cu transporters.
Cu-transporting MCF proteins were identified using genetic screens based on limiting Cu availability with the addition of Ag as a competitor. At concentrations of 150 μM, Ag inhibits Cu uptake and results in decreased COX activity. To elicit the same defect in cells lacking PIC2 only 75–100 μM Ag is required, suggesting a loss of high-affinity transport. Mrs3 was identified as a lower affinity Cu transporter based on additive phenotypes. Yeast cells lacking PIC2 and MRS3 grown under mild Cu chelation without the addition of Ag had decreased COX, decreased IM-SOD1 activity and lower mitochondrial Cu uptake and accumulation.