[Presence of a lysis factor of mitochondria in rabbit reticulocytes]

Incubation of isolated rat liver and beef heart mitochondria together with a fraction of nonhaemoglobin proteins from rabbit reticulocytes (reti-AS) leads to drastic structural damages such as a deformation and disruption of the outer membranes as well as a disappearance of the cristae structure. The vacuolized forms obtained in this manner reveal striking similarities to the known degradation ones of reticulocyte mitochondria in situ and after isolation of them. The extent of the lysis of mitochondria depends on the amount of reti-AS and on the temperature. The lysis is caused by a protein factor (MLF) which is not identical with the respiratory inhibitor RF present in the reti-AS as well. Like RF, MLF disappears during the maturation process of reticulocytes to erythrocytes. MLF triggers the penetration of RF into the mitochondria and thus the inhibition of the succinate oxidase and the NADH oxidase activity. EDTA inactivates RF but not MLF. MLF is bound to electron transfer particles from beef heart mitochondria. The experimental conditions used are supposed to be a model for the degradation of mitochondria in situ during the maturation process of reticulocytes.