Mechanisms of γ-Globulin Synthesis

Summary

Protein synthesis has been studied in lymph node cells obtained from rabbits hyperimmunized to bacteriophage T₂. Provided ribonuclease activity was inhibited, almost all nascent protein synthesis occurred on polyribosomes. Pretreatment with 1 µg/ml actinomycin D, 7 hr prior to labeling, caused an 80% reduction of polyribosome-directed protein synthesis. Pulse-labeling studies of similar cell populations indicated that depression of RNA synthesis preceded the reduction of protein and γ-globulin synthesis. When actinomycin D-treated cells were infected with Newcastle disease virus (an RNA virus), cells which had already ceased to make RNA and protein started to synthesize these macromolecules at rapid rates. Thus, the final steps of γ-globulin synthesis by immune lymph node cells appear similar to those of protein synthesis in HeLa cells.