Degradation of mitochondria by cytosolic factors in reticulocytes.

The degradation process of mitochondria in rabbit reticulocytes proceeds predominately directly in the cytosol rather than in secondary lysosomes as judged by electronmicroscopy. At least five cytosolic protein factors are present in reticulocytes, which could be related to the degradation of mitochondria: the two inhibitory proteins of the respiratory chain RF and RC and three enzymes which cause a lysis of mitochondria in vitro (lipoxygenase, proteinase, phospholipase A). The properties of these factors are the subject of this paper. A hypothetic scheme of the degradation of mitochondria in reticulocytes is proposed. The degradation of mitochondria in reticulocytes is viewed as a complex interplay of various cytosolic factors and the functional state of the mitochondrial membranes. The lipoxygenase damages the membranes and triggers the penetration of the respiratory inhibitors. In this manner, a catastrophic cycle is initiated which leads to the complete breakdown of the mitochondria.