Human copper chaperone for superoxide dismutase 1 mediates its own oxidation-dependent import into mitochondria

The accumulation of superoxide in mitochondria is counteracted by superoxide dismutase 1 and its activating chaperone CCS1. Suzuki et al. show that in human cells, mature CCS1 itself mediates CCS1 import and helps to oxidize CCS1 and SOD1 in the mitochondrial intermembrane space.