ATP-dependent proteolysis of mitochondria of reticulocytes.

Since its discovery in 1956 the physiological function of the ATP-dependent proteolysis in reticulocytes has become an area of intensive interest. The evidence that mitochondria are the main substrate of the process during maturation of reticulocytes is summarized. The large consumption of ATP related to the degradation of mitochondria is discussed in context with possible mechanisms for ATP requirement. A novel ATP-dependent peptide release from reticulocyte mitochondria, which may be the first step in the degradation of the organelles, is demonstrated. Ubiquitin and tRNA are involved in the degradation process. Their roles, however, are not yet clear. The whole degradation cascade consisting of lipoxygenase, mitochondria susceptibility factor and ATP-dependent proteolysis, may function as a defense system against uncontrolled degradation of mitochondria in reticulocytes.