MitoCPR—A surveillance pathway that protects mitochondria in response to protein import stress

The mitoCPR unclogs mitochondria The import of proteins into mitochondria is essential for cell viability. How cells respond when mitochondrial protein import is impaired is poorly understood. Weidberg and Amon showed that upon mitochondrial import stress, yeast cells mounted a response known as the mitoCPR. mitoCPR was activated when mitochondrial protein import was impaired and unimported precursors accumulated on the organelle's surface. mitoCPR restored mitochondrial functions by clearing stalled proteins from the import channels. It did this by inducing expression of Cis1, which recruited the adenosine triphosphatase Msp1 to import channels to remove unimported precursors and target them for degradation by the proteasome. Science , this issue p. eaan4146