Light-induced Changes in the Pattern of Protein Synthesis during the Early Stages of Greening of Etiolated Maize Leaves

The effect of light on protein synthesis during the early stages of greening of etiolated maize (Zea mays) leaves was studied using double labeling with leucine and fractionation of proteins by gel filtration and acrylamide gel electrophoresis. The incorporation of labeled leucine into a relatively small number of plastid proteins is effected within the first 30 to 60 minutes of illumination. These proteins do not accumulate with time. When illumination is prolonged, additional proteins are effected.Experiments using inhibitors of protein synthesis suggest that at least some of the proteins effected by 1 hour of illumination might be synthesized in the cytoplasm and not in plastids. Actinomycin D inhibits the incorporation of labeled leucine into some of the protein fractions, but enhances the incorporation into other fractions far above the effect exerted by light.