Proteolysis during in vitro-maturation of rabbit reticulocytes

We investigated the ATP-dependent proteolysis, cytochrome oxidase and the succinate-cytochrome c-oxidoreductase in reticulocytes under different conditions of incubation in vitro at 37 degrees C. Under standard conditions the proteolysis virtually stops after 4 h. The degradation of the stroma proteins amounted to 30-65% depending on the percentage of reticulocytes. The decrease of the cytochrome oxidase amounted to 70% after 20 h of incubation. Inhibition of the cytosolic reticulocyte lipoxygenase (LOX) by the reversible inhibitor salicylhydroxamate (SHAM) leads to an inhibition of both proteolysis and cytochrome oxidase activity by about two-thirds after 20 h of incubation. In the presence of a Ca++-ionophore the rate of proteolysis was increased by 33%, while the cytochrome oxidase and succinate-cytochrome c-oxidoreductase activities both decreased more rapidly than in the control experiments.