Researchers have identified the protein that carries copper into mitochondria. These findings, published last week in the Journal of Biological Chemistry, expand our current understanding of how copper is distributed and used in the cell.
Copper is essential for the functioning of numerous enzymes and in mitochondria is required for building cytochrome c oxidase (COX), which forms the last step of the electron transport chain. One thing that has baffled scientists is how this copper gets across the membrane in mitochondria without interfering with other proteins or disrupting other targets with a high chance of binding copper.
Researchers from Auburn University and the University of Saskatchewan performed experiments in human and murine cell lines to identify SLC25A3 as copper’s transporter through the mitochondria. This came as a surprise as SLC25A3 is known to transport phosphate, a negatively charged ion, whereas copper ions hold a positive charge.
SLC25A3 mutations have previously been identified in poorly understood genetic disorders involving dysfunctional heart and muscle fibers that lead to enlarged hearts and low muscle tone. Since these tissues require large amounts of energy, these results open the door to investigating whether the disorders are related to insufficient copper transportation in mitochondria.