Proteolytic enzymes in mitochondria

The current interest in mitochondrial proteases is based on the recognition that these enzymes are actually involved in very important regulatory and metabolic roles inside the organelle. It has been formerly assumed that functions such as limited proteolysis, continuous turnover to regulate protein levels and selective elimination of defective and/or exceeding protein molecules, which have been clearly demonstrated in the intact cell, are likely to be operative within the physical boundaries of a well delimited organelle as the mitochondrion is. Consistent evidence has gradually accumulated on the existence of intramitochondrial proteolytic systems and this has led to a systematic search for the responsible proteases. The present discussion gives a brief up-to-date account of the existing information on mitochondrial proteolysis and describes the contribution to this field made by our own research.