Inhibition of Protein Synthesis in Cultured Tobacco Cells by Ultraviolet Radiation

Ultraviolet (254 nm) irradiation of liquid‐cultured tobacco cells strongly and quickly inhibited their ability to incorporate labeled amino acids into protein. An incident dose of only 388 J/m 2 reduced incorporation to 37 per cent of the original rate. The effect on amino acid incorporation did not seem to depend on inhibition of amino acid uptake, inhibition of the supply of nucleoside triphosphates, or inhibition of the supply of messenger RNA to cytoplasmic ribosomes.