Studies on the activation of the heme-stabilized translational inhibitor of reticulocyte lysates by oxidized glutathione and NADPH depletion

The translational inhibition produced by addition of oxidized glutathione (GSSG) to hemin-containing reticulocyte lysates and the accompanying phosphorylation of the alpha subunit of the polypeptide chain initiation factor eIF-2 can be prevented or reversed by NADPH generators, including glucose 6-phosphate, deoxyglucose 6-phosphate, fructose 6-phosphate, NADPH itself, and also by dithiols, e.g., dithiothreitol, but not by reduced glutathione (GSH) or other monothiols, e.g., 2-mercaptoethanol. The same is true of the inhibition caused by addition of glutamate dehydrogenase, alpha-ketoglutarate, and NH4+, which may be entirely due to NADPH depletion via the reaction.