Light‐induced Activation of Cytoplasmic Protein Synthesis in Verticillium agaricinum

Abstract The level of protein synthetic activity in dark‐grown cultures of Verticillium agaricinum was significantly enhanced by light. As expected the enhancement of protein synthetic activity was accompanied by a transformation of cytoplasmic monoribosomes to polyribosomes. Amino acid incorporation studies utilizing the synthetic mRNA, poly (U), suggest that the transformation was preceded by an activation of pre‐existing ribosomes. The change in ribosome activity related, at least in part, to an increase in the level of peptidyl‐tRNA associated with the ribosomes. In this regard the response of V. agaricinum ribosomes was similar to ribosome activation in several higher plant systems. The initial response at the level of the ribosome remains to be elucidated.