The effect of nucleoproteins upon amino acid incorporation into protein in Walker 256 cells.

The effects of deoxyribonucleoprotein, histories, and polyL-lysine on amino acid uptake and incorporation into protein in Walker 256 tumor cells have been investigated. When Walker 256 tumor cells were incubated with deoxyribonucleoprotein, histories, or poly-L-lysine there was a reduction in the amount of 14C-labeled amino acids found in the hot 5% trichloroacetic acid-insoluble fraction. The very lysine-rià ́h histone fractions produced the greatest percent of inhibition. Homologous histones at low concentrations were strongly inhibitory while homologous deoxyribonucleoproteins gave slightly less inhibition. The inhibition produced by deoxyribonucleoprotein could be partially removed by washing the cells with cold incubation medium. However, the inhibition caused by histones remained even after washing with cold incubation medium. These findings suggest that it is the histone portion of the nucleoprotein that is responsible for the observed inhibition of protein elaboration and that the effect is either an intracellular or membrane phenomenon.